Request and Response Method for Probing MLD, Station, and Access Point

ABSTRACT

Embodiments of this application provide a probe request and response technology between a station and a plurality of access point multi-link devices (AP MLDs). During implementation of this application, a station may obtain communication parameters of a plurality of APs of one or more AP MLDs by sending one probe request frame, to obtain communication parameters of the AP MLD on a plurality of links, thereby efficiently implementing association between the station and the AP MLD or establishing multi-link transmission between the station and the AP MLD.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2021/104327, filed on Jul. 2, 2021, which claims priority toChinese Patent Application No. 202010634151.8, filed on Jul. 2, 2020.The disclosures of the aforementioned applications are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

This application relates to the field of communication technologies, andin particular, to request and response methods for probing an MLD in awireless local area network, a station, and an access point.

BACKGROUND

To greatly increase a service transmission rate of a wireless local areanetwork (WLAN) system, an orthogonal frequency division multiple access(OFDMA) technology is further used in the Institute of Electrical andElectronics Engineers (IEEE) 802.11ax standard based on an existingorthogonal frequency division multiplexing (OFDM) technology. The OFDMAtechnology supports a plurality of nodes to simultaneously send andreceive data, to achieve multi-station diversity gains. In 2017 when the802.11ax standard is finalized, the Federal Communications Commission(FCC) of the United States released a new free frequency band 5925-7125MHz, which is referred to as 6 GHz in the following. In this case,802.11ax standard workers expand an operating range of802.11ax-compliant devices from 2.4 GHz and 5 GHz to 2.4 GHz, 5 GHz, and6 GHz in the 802.11ax project authorization request (ProjectAuthorization Request, PAR).

IEEE 802.11 next-generation Wi-Fi protocol (extremely high throughput,EHT) devices need to be forward compatible. Therefore, they also supportoperating spectrums of 802.11ax-compliant devices, that is, 2.4 GHz, 5GHz, and 6 GHz frequency bands. Channel division is performed based onthe newly opened free 6 GHz frequency band, and a supportable bandwidthmay exceed a maximum bandwidth 160 MHz supported in 5 GHz, for example,may be 320 MHz. In IEEE 802.11ax next-generation Wi-Fi Extremely HighThroughput protocol, a peak throughput may also be increased by usingmore streams, for example, increasing a quantity of streams to 16,through cooperation with a plurality of frequency bands (2.4 GHz, 5 GHz,and 6 GHz), or in another manner, in addition to using an ultra-highbandwidth. On a same frequency band, a peak throughput may be furtherincreased through cooperation of a plurality of channels or in anothermanner. This reduces a service transmission delay. In the following, aplurality of frequency bands or a plurality of channels are collectivelyreferred to as a plurality of links. Although a plurality of links areconfigured for 802.11ax Wi-Fi and earlier Wi-Fi that have a sameoperating frequency band, a different basic service set (BSS) is usuallyestablished for each of the plurality of links, and communication with astation in a BSS to which the link belongs can be performed on only onelink at the same time.

Main functions of 802.11ax and an earlier multiple basic service setidentifier (BSSID) technology are to virtualize one physical AP into aplurality of logical APs, that is, forming a plurality of virtualnetworks. Each virtual network is used to manage a different station.Similar to AP products in a current Wi-Fi scenario, an AP can bevirtualized into a home AP and a guest AP.

When the multiple BSS ID technology is applied to a multi-link device(MLD), how to implement probing and association between a non-accesspoint station (non-AP STA) MLD and an access point station (AP STA) MLDis a technical problem that is being studied by technical personnel.

SUMMARY

Embodiments of this application disclose a requesting method for probinga multi-link device in a WLAN, a response method for probing amulti-link device, and a related apparatus.

A first aspect of this application provides a station in a wirelesslocal area network WLAN, including: a processor, configured to generatethe probe request frame, where the probe request frame is used torequest a first AP to feed back a communication parameter of an AP MLDin which the first AP is located, the first AP is a nontransmitted basicservice set identifier nontransmitted BSSID AP, and the communicationparameter of the AP MLD is communication parameters of a plurality oflinks supported by the AP MLD; and a transceiver, configured to send theprobe request frame to the first AP.

A second aspect of this application provides a requesting method forprobing an access point multi-link device, where the method is executedby a station in a wireless local area network WLAN, and the methodincludes: generating the probe request frame, where the probe requestframe is used to request a first AP to feed back a communicationparameter of an AP MLD in which the first AP is located, the first AP isa nontransmitted basic service set identifier nontransmitted BSSID AP,and the communication parameter of the AP MLD is communicationparameters of a plurality of links supported by the AP MLD; and sendingthe probe request frame to the first AP.

In the station provided in the first aspect or the method provided inthe second aspect, the probe request frame carries first indicationinformation, and the first indication information indicates to feed backthe communication parameter of the AP MLD in which the first AP islocated.

According to the station provided in the first aspect or the methodprovided in the second aspect, the first indication information iscarried in any one of the following elements: a multi-link elementmulti-link element, a request MLD element request MLD element, and aknown MLD element known MLD element.

The station provided in the first aspect or the method provided in thesecond aspect further includes: receiving a probe response frame from asecond AP, where the probe response frame carries the communicationparameter of the AP MLD in which the first AP is located.

In an implementation, the communication parameter of the AP MLD in whichthe first AP is located includes communication parameters correspondingto all or some links corresponding to the AP MLD.

In an implementation, the probe request frame further carries a fieldindicating a link identifier of the AP MLD, and the field indicating thelink identifier of the AP MLD indicates the first AP to feed back acommunication parameter of a corresponding link in the AP MLD in whichthe first AP is located.

In an implementation, the field indicating the link identifier of the APMLD is a link configuration element or a link index bitmap.

According to the station provided in the first aspect or the methodprovided in the second aspect, the probe response frame carries thecommunication parameter of the first AP by using a multiple BSSIDelement multiple BSSID element, and carries a communication parameter ofanother AP in the AP MLD of the first AP in a multilink element of anontransmitted BSSID profile corresponding to the first AP.

According to the station provided in the first aspect or the methodprovided in the second aspect, a non-inheritance element of the proberequest frame further carries indication information indicates torequest some information elements of the AP MLD.

In the station provided in the first aspect or the method provided inthe second aspect, any one of the multi-link element, the request MLDelement, and the known MLD element further carries the indicationinformation indicates to request the some information elements of the APMLD.

During implementation of the station in the first aspect or the methodin the second aspect of this application, when a non-AP STA wants torequest a communication parameter of an AP MLD, the non-AP STA may senda probe request frame to a logical AP of the AP MLD. Even if the logicalAP is configured as a nontransmitted BSSID, another transmitted BSSID APbelonging to a same MSSID set may respond to the probe request frame, toreply with the communication parameter of the AP MLD. This can resolve atechnical problem in the conventional technology that a communicationparameter of an AP MLD on another link cannot be obtained by sending theprobe request frame.

A third aspect of this application provides a station in a wirelesslocal area network WLAN, including: a processor, configured to generatethe probe request frame, where the probe request frame is used torequest a second AP to feed back a communication parameter that is of anAP MLD and that is related to the second AP, the second AP is atransmitted basic service set identifier transmitted BSSID AP, and thecommunication parameter of the AP MLD is communication parameters of aplurality of links supported by the AP MLD; and a transceiver,configured to send the probe request frame to the second AP.

A second aspect of this application provides a requesting method forprobing an access point multi-link device, where the method is executedby a station in a wireless local area network WLAN, and the methodincludes: generating the probe request frame, where the probe requestframe is used to request a second AP to feed back a communicationparameter that is of an AP MLD and that is related to the second AP, thesecond AP is a transmitted basic service set identifier transmittedBSSID AP, and the communication parameter of the AP MLD is communicationparameters of a plurality of links supported by the AP MLD; and sendingthe probe request frame to the second AP.

In the station according to the third aspect of this application or themethod according to the fourth aspect, the probe request frame carriessecond indication information, and the second indication informationindicates the second AP to feed back the communication parameter that isof the AP MLD and that is related to the second AP.

In the station according to the third aspect or the method according tothe fourth aspect of this application, the communication parameter thatis of the AP MLD and that is related to the second AP includes at leastone of the following:

a communication parameter of the AP MLD in which the second AP islocated;

a communication parameter of an AP MLD in which another AP belonging toa same multiple transmitted basic service set identifier MBSSID set asthe second AP is located; or

a communication parameter of an AP MLD in which another AP collocatedwith the second AP is located.

According to the station of the third aspect or the method of the fourthaspect of this application, the second indication information is carriedin the probe request frame, the second indication information indicatesan MLD identifier or an MLD address, and the MLD identifier or the MLDaddress indicates the second AP to feed back a communication parameterof an AP MLD corresponding to the MLD identifier or the MLD address.

According to the station in the third aspect or the method in the fourthaspect of this application, the second indication information is carriedin the probe request frame, and the second indication informationindicates, in a bitmap manner, the AP MLD related to the second AP thatis requested. The indicating, in the bitmap manner, the requested AP MLDmay be performing indication by using a BSSID identifier bitmap field.

In the station according to the third aspect of this application or themethod according to the fourth aspect, the second indication informationcarries any one of the following elements: a multi-link elementmulti-link element, a request MLD element request MLD element, and aknown MLD element known MLD element.

During implementation of this embodiment of this application, when anon-AP STA wants to request a communication parameter of an AP MLD, thenon-AP STA may send a probe request frame to an AP configured as atransmitted BSSID AP. The transmitted BSSID AP may reply a communicationparameter of an MLD in which another AP belonging to a same MSSID set islocated and/or a communication parameter of an MLD in which another APcollocated with the transmitted BSSID AP is located. Therefore, atechnical problem in the conventional technology that the MLDcommunication parameter of the another AP cannot be obtained by sendingthe probe request frame is resolved.

A fifth aspect of this application provides a first access point AP in awireless local area network WLAN, where the first AP is a nontransmittedbasic service set identifier nontransmitted BSSID AP, and the first APincludes: a transceiver, configured to receive a probe request framefrom a station, where the probe request frame is used to request thefirst AP to feed back a communication parameter of an AP MLD in whichthe first AP is located, and the communication parameter of the AP MLDis communication parameters of a plurality of links supported by thefirst AP.

The transceiver is further configured to request a second AP thatbelongs to a same MBSSID set as the first AP to assist the first AP tofeed back a probe response frame to the station, where the proberesponse frame carries the communication parameter of the AP MLD.

A sixth aspect of this application provides a response method forprobing an access point multi-link device, where the method is appliedto a first access point AP in a wireless local area network WLAN, thefirst AP is a nontransmitted basic service set identifier nontransmittedBSSID AP, and the method includes: receiving a probe request frame froma station, where the probe request frame is used to request the first APto feed back a communication parameter of an AP MLD in which the firstAP is located, and the communication parameter of the AP MLD iscommunication parameters of a plurality of links supported by the firstAP; and requesting a second AP that belongs to a same MBSSID set as thefirst AP to assist the first AP to feed back a probe response frame tothe station, where the probe response frame carries the communicationparameter of the AP MLD.

A seventh aspect of this application provides a second access point APin a wireless local area network WLAN, where the second AP is atransmitted basic service set identifier transmitted BSSID AP, and thesecond AP includes: a transceiver, configured to receive a probe requestframe from a first AP, where the probe request frame is used to requestthe second AP to assist the first AP to feed back a communicationparameter of an AP MLD in which the second AP is located, the first APis a nontransmitted basic service set identifier nontransmitted BSSIDAP, and belongs to a same MBSSID set as the second AP, and acommunication parameter of the AP MLD is communication parameters of aplurality of links supported by the AP MLD; and a processor, configuredto generate a probe response frame, where the probe response framecarries the communication parameter of the AP MLD.

An eighth aspect of this application provides a response method forprobing an access point multi-link device, where the method is appliedto a second access point AP in a wireless local area network WLAN, thesecond AP is a transmitted basic service set identifier transmittedBSSID AP, and the method includes: receiving a probe request frame froma first AP, where the probe request frame is used to request the secondAP to assist the first AP to feed back a communication parameter of anAP MLD in which the second AP is located, the first AP is anontransmitted basic service set identifier nontransmitted BSSID AP, andbelongs to a same MBSSID set as the second AP, and a communicationparameter of the AP MLD is communication parameters of a plurality oflinks supported by the AP MLD; and generating a probe response frame,where the probe response frame carries the communication parameter ofthe AP MLD.

According to the access point provided in the seventh aspect of thisapplication or the method provided in the eighth aspect, the proberesponse frame carries some information elements in the communicationparameter that is of the AP MLD and that is related to the second AP.

During implementation of the access point provided in the seventh aspector the method provided in the eighth aspect, a nontransmitted BSSID APmay feed back, by using another AP collocated with the nontransmittedBSSID AP or another AP belonging to a same MBSSID set as the non-AP AP,a communication parameter of an AP MLD in which the nontransmitted BSSIDAP is located to a non-AP STA.

A ninth aspect of this application provides a second access point AP ina wireless local area network WLAN, where the second AP is a transmittedbasic service set identifier transmitted BSSID AP, and the second APincludes: a transceiver, configured to receive a probe request framefrom a station, where the probe request frame is used to request asecond AP to feed back a communication parameter that is of an AP MLDand related to the second AP, and the communication parameter of the APMLD is communication parameters of a plurality of links supported by theAP MLD; a processor, configured to generate a probe response frame,where the probe response frame carries the communication parameter thatis of the AP MLD and that is related to the second AP; and atransceiver, configured to send the probe response frame to the station.

A tenth aspect of this application provides a response method forprobing an access point multi-link device, where the method is appliedto a second access point AP in a wireless local area network WLAN, thesecond AP is a transmitted basic service set identifier transmittedBSSID AP, and the method includes: receiving a probe request frame froma station, where the probe request frame is used to request a second APto feed back a communication parameter that is of an AP MLD and relatedto the second AP, and the communication parameter of the AP MLD iscommunication parameters of a plurality of links supported by the APMLD; generating a probe response frame, where the probe response framecarries the communication parameter that is of the AP MLD and that isrelated to the second AP; and sending the probe response frame to thestation.

According to the access point provided in the ninth aspect of thisapplication or the method provided in the tenth aspect, thecommunication parameter that is of the AP MLD and that is related to thesecond AP includes at least one of the following:

a communication parameter of the AP MLD in which the second AP islocated;

a communication parameter of an AP MLD in which another AP belonging toa same multiple transmitted basic service set identifier MBSSID set asthe second AP is located; or

a communication parameter of an AP MLD in which another AP collocatedwith the second AP is located.

According to the access point provided in the ninth aspect of thisapplication or the method provided in the tenth aspect. When the proberequest frame carries second indication information, and the secondindication information indicates an MLD identifier or an MLD address,the probe response frame carries a communication parameter of the AP MLDcorresponding to the MLD identifier or the MLD address of the proberequest frame.

According to the access point provided in the ninth aspect of thisapplication or the method provided in the tenth aspect, the proberequest frame carries the second indication information. When the secondindication information indicates, in a bitmap manner, the AP MLDrequested by the probe request frame, a communication parameter of theAP MLD that is indicated in a bitmap manner is carried in the proberesponse frame. The requested AP MLD indicated in the bitmap manner maybe a BSSID identifier bitmap field. Each bit in the BSSID identifierbitmap represents a corresponding AP MLD.

According to the access point provided in the ninth aspect of thisapplication or the method provided in the tenth aspect, the proberesponse frame carries a communication parameter of an AP MLD in which afirst AP related to the second AP is located, and the first AP is afirst AP belonging to the same MSSID set as the second AP, and/or afirst AP collocated with the second AP.

According to the access point provided in the ninth aspect of thisapplication or the method provided in the tenth aspect, the proberesponse frame carries the communication parameter of the first AP byusing a multiple BSSID element multiple BSSID element, and carries acommunication parameter of another AP in the AP MLD of the first AP in amulti-link element of a nontransmitted BSSID profile nontransmittedBSSID profile corresponding to the first AP.

According to the access point provided in the ninth aspect of thisapplication or the method provided in the tenth aspect, the proberesponse frame carries some information elements in the communicationparameter that is of the AP MLD and that is related to the second AP.

The station in the first aspect, the station in the third aspect, thefirst access point provided in the fifth aspect, the second access pointprovided in the seventh aspect, and the second access point provided inthe ninth aspect may be a chip. The processing unit may be a processingcircuit of the chip. The transceiver unit may be an input/outputinterface circuit. The processing circuit may be configured to processsignaling or data information provided by the input/output interfacecircuit. The input/output interface circuit may be configured toinput/output data or signaling information for the chip.

According to an eleventh aspect of embodiments of this application, acomputer-readable storage medium is provided. The computer-readablestorage medium stores computer program code. When the computer programis run on a processor, the processor is enabled to perform the method inany one of the second aspect, the fourth aspect, the sixth aspect, theeighth aspect, the tenth aspect, and the corresponding possibleimplementations.

According to a twelfth aspect of embodiments of this application, acomputer program product is provided. The program product stores acomputer program (instructions) executed by the foregoing processor.When the computer program is run on the processor, the processor isenabled to perform the method in any one of the second aspect, thefourth aspect, the sixth aspect, the eighth aspect, the tenth aspect,and the corresponding possible implementations.

According to a thirteenth aspect of embodiments of this application, acommunication apparatus is provided. The apparatus includes a processor,and may further include a transceiver and a memory. The transceiver isconfigured to receive and send information, or is configured tocommunicate with another network element. The memory is configured tostore a computer program (instructions). The processor is configured toexecute the computer program, to support the communication apparatus toperform the method in any one of the second aspect, the fourth aspect,the sixth aspect, the eighth aspect, the tenth aspect, and thecorresponding possible implementations.

According to a fourteenth aspect of embodiments of this application, acommunication apparatus is provided. The apparatus may exist in aproduct form of a chip. A structure of the apparatus includes aprocessor, and may further include a memory. The memory is configured tobe coupled to the processor, and store a program (instructions) and datathat are necessary for the apparatus. The processor is configured toexecute the computer program stored in the memory, to support thecommunication apparatus to perform the method in any one of the secondaspect, the fourth aspect, the sixth aspect, the eighth aspect, thetenth aspect, and the corresponding possible implementations.Optionally, the memory may be located in the processor, and is aninternal storage. Alternatively, the processor may be located outsidethe processor, is coupled to the processor, and is an external storage.

BRIEF DESCRIPTION OF THE DRAWINGS

The following describes accompanying drawings used in embodiments ofthis application.

FIG. 1 is a schematic diagram of a structure of a communication systemaccording to an embodiment of this application;

FIG. 2 a is a schematic diagram of a structure of a multi-link deviceaccording to an embodiment of this application;

FIG. 2 b is a schematic diagram of a structure of another multi-linkdevice according to an embodiment of this application;

FIG. 2C is a schematic diagram of a structure of still anothermulti-link device according to an embodiment of this application;

FIG. 3 a is a schematic diagram of multi-link communication according toan embodiment of this application;

FIG. 3 b is another schematic diagram of multi-link communicationaccording to an embodiment of this application;

FIG. 4 is a schematic diagram of forming an MBSSID set by a plurality ofmulti-link devices in a WLAN according to an embodiment of thisapplication;

FIG. 5 is a schematic flowchart of a multi-link device probing method ina WLAN according to an embodiment of this application;

FIG. 6 is another schematic flowchart of a multi-link device probingmethod in a WLAN according to an embodiment of this application;

FIG. 7 a to FIG. 7 d are schematic diagrams of structures of multi-linkelements according to an embodiment of this application;

FIG. 8 is a schematic diagram of a structure of a subelement in amultilink element according to an embodiment of this application;

FIG. 9 a to FIG. 9 e are schematic diagrams of structures of severalmultilink elements according to an embodiment of this application;

FIG. 10 is a schematic structural diagram of a multiple BSSID elementaccording to an embodiment of this application;

FIG. 11 a and FIG. 11 b are schematic diagrams of structures of requestMLD elements according to an embodiment of this application;

FIG. 12 a to FIG. 12C are schematic diagrams of structures of known MLDelement according to an embodiment of this application;

FIG. 13 is a schematic diagram of a structure a probing elementaccording to an embodiment of this application;

FIG. 14 is a schematic diagram of a structure of a communicationapparatus according to an embodiment of this application; and

FIG. 15 is a schematic diagram of a structure of another communicationapparatus according to an embodiment of this application.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The following first describes related technologies in this application,and then describes embodiments of this application with reference to theaccompanying drawings.

An embodiment of this application provides a communication methodapplied to a wireless communication system. The wireless communicationsystem may be a wireless local area network (WLAN) or a cellularnetwork. The method may be performed by a communication device in thewireless communication system or a chip or a processor in thecommunication device. The communication device may be a wirelesscommunication device that supports concurrent transmission performed ona plurality of links. For example, the communication device is referredto as a multi-link device or a multi-band device. For example, in thewireless local area network, the communication device supportscommunication performed by using IEEE 802.11 series protocols, and theIEEE 802.11 series protocols includes: 802.11be, 802.11ax, or802.11a/b/g/n/ac.

1. A Multi-Link Device MLD is Also Referred to as a Multi-Band Device.

The multi-link device MLD includes one or more affiliated stations, andthe affiliated station is a logical station. “A multi-link deviceincludes an affiliated station” is also briefly described as “Amulti-link device includes a station” in embodiments of thisapplication. An affiliated station may be an access point (AP) or anon-access point station (non-AP STA). For ease of description, in thisapplication, a multi-link device whose affiliated station is an AP maybe referred to as a multi-link AP, a multi-link AP device, or an APmulti-link device, and a multi-link device whose affiliated station is anon-AP STA may be referred to as a multi-link STA, a multi-link STAdevice, or a STA multi-link device.

The multi-link device MLD may implement wireless communication incompliance with 802.11 series protocols, for example, in compliance withthe Extremely High Throughput (EHT) protocol, or in compliance with802.11be-based or 802.11be-compatible protocol, thereby implementingcommunication with another device. The another device may be amulti-link device or may not be a multi-link device.

Each logical station may operate on one link, and a plurality of logicalstations are allowed to operate on a same link. A link identifiermentioned below identifies or represents one station operating on onelink. In other words, if there is more than one logical station on onelink, more than one link identifier is required to identify or representthe logical stations. The link mentioned below sometimes also indicatesa station operating on the link. If data transmission is performedbetween a multi-link device and another multi-link device, beforecommunication, the multi-link device and the another multi-link devicemay first negotiate or communicate with each other about acorrespondence between a link identifier and a link or a station on alink, or an AP multi-link device indicates a correspondence between alink identifier and a link or a station on a link through a broadcastmanagement frame, for example, a beacon frame. Therefore, during datatransmission, a link identifier is carried without transmitting a largeamount of signaling information to indicate a link or a station on alink. This reduces signaling overheads and improves transmissionefficiency.

The following uses an example on which the foregoing one multi-linkdevice is an AP multi-link device, and the foregoing another multi-linkdevice is a STA multi-link device for description.

For example, when the AP multi-link device establishes a BSS, amanagement frame, for example, a beacon frame, sent by the AP multi-linkdevice carries an element including a plurality of link identifierinformation fields. Each link identifier information field may indicatea correspondence between a link identifier and a station operating on alink. Each link identifier information field includes a link identifier,and further includes one or more of a MAC address, an operating class,and a channel number. One or more of the MAC address, the operatingclass, and the channel number may identify a link. For another example,in a multi-link association establishment process, the AP multi-linkdevice and the STA multi-link device negotiate for a plurality of linkidentifier information fields. In subsequent communication, the APmulti-link device or the STA multi-link device identifies or representsa station in the multi-link device by using a link identifier. The linkidentifier may further represent one or more attributes of a MACaddress, an operating set, and a channel number of the station. The MACaddress may alternatively be an association identifier of the associatedAP multi-link device. Optionally, if a plurality of stations operate onone link, meanings identified by a link identifier (link ID) include notonly an operation set in which the link is located and a channel number,but also an identifier of a station operating on the link, for example,a MAC address or an association identifier (AID) of a station.

FIG. 1 is a diagram of an application scenario of an embodiment of thisapplication by using a wireless local area network as an example. Theapplication scenario includes: a first station 101, a second station102, a third station 201, and a fourth station 202. The first station101 may communicate with the second station 102 by using a plurality oflinks, and the third station 201 may communicate with the fourth station202 by using a plurality of links, thereby improving a throughput. Asshown in FIG. 1 , for example, the first station 101 is a multi-link APdevice, the second station 102 is a multi-link STA device, the thirdstation 201 is a multi-link AP device, and the fourth station 202 is amulti-link STA device. Certainly, the second station 102 and/or thefourth station 202 may alternatively be single-link STA devices. Inaddition, in a scenario, the first station 101 is an AP multi-linkdevice, and the second station 102 is a STA multi-link device or astation (for example, a single-link station). In another scenario, thefirst station 101 is a STA multi-link device, and the second station 102is an AP (for example, a single-link AP) or an AP multi-link device. Instill another scenario, the first station 101 is an AP multi-linkdevice, and the second station 102 is an AP multi-link device or an AP.In still another scenario, the first station 101 is a STA multi-linkdevice, and the second station 102 is a STA multi-link device or a STA.Certainly, the wireless local area network may further include anotherdevice. A quantity and a type of devices shown in FIG. 1 are merelyexamples.

FIG. 2 a and FIG. 2 b are schematic diagrams of structures of an APmulti-link device and a STA multi-link device that participate incommunication. 802.11 standards focus on 802.11 physical layer (PHY) andmedia access control (MAC) layer parts of an AP multi-link device and aSTA multi-link device (such as a mobile phone and a notebook computer).

As shown in FIG. 2 a , a plurality of APs included in the AP multi-linkdevice are independent of each other at a low MAC layer and a PHY layer,and are also independent of each other at a high MAC layer. A pluralityof STAs included in the STA multi-link device are independent of eachother at a low MAC layer and a PHY layer, and are also independent ofeach other at a high MAC layer.

As shown in FIG. 2 b , a plurality of APs included in the AP multi-linkdevice are independent of each other at a low MAC layer and a PHY layer,and share a high MAC layer. A plurality of STAs included in the STAmulti-link device are independent of each other at a low MAC layer and aPHY layer, and share a high MAC layer.

Certainly, the STA multi-link device may use a structure on which highMAC layers are independent of each other, and the AP multi-link devicemay use a structure on which a high MAC layer is shared. Alternatively,the STA multi-link device may use a structure in which a high MAC layeris shared, and the AP multi-link device may use a structure in whichhigh MAC layers are independent of each other. For example, the high MAClayer or the low MAC layer may be implemented by one processor in a chipsystem of the multi-link device, or may be implemented by differentprocessing modules in a chip system.

For example, the multi-link device in this embodiment of thisapplication may be a single-antenna device, or may be a multi-antennadevice. For example, the multi-link device may be a device with morethan two antennas. The quantity of antennas included in the multi-linkdevice is not limited in the embodiments of this application. Forexample, in FIG. 2 c , the AP multi-link device is a multi-antennadevice and the STA multi-link device is a single-antenna device. In thisembodiment of this application, the multi-link device may allow servicesof a same access type to be transmitted on different links, or evenallow same data packets to be transmitted on different links.Alternatively, the multi-link device may not allow services of a sameaccess type to be transmitted on different links, but may allow servicesof different access types to be transmitted on different links.

Frequency bands on which the multi-link device operates may include butare not limited to sub 1 GHz, 2.4 GHz, 5 GHz, 6 GHz, and a highfrequency 60 GHz. FIG. 3 a and FIG. 3 b are two schematic diagrams ofcommunication between a multi-link device and another device in awireless local area network through a plurality of links.

FIG. 3 a shows a scenario in which an AP multi-link device 101communicates with a STA multi-link device 102. The AP multi-link device101 includes an affiliated AP 101-1 and an affiliated AP 101-2, the STAmulti-link device 102 includes an affiliated STA 102-1 and an affiliatedSTA 102-2, and the AP multi-link device 101 communicate with the STAmulti-link device 102 in parallel on a link 1 and a link 2.

FIG. 3 b shows a scenario in which an AP multi-link device 101communicates with a STA multi-link device 102, a STA multi-link device103, and a STA 104. The AP multi-link device 101 includes an affiliatedAP 101-1 to an affiliated AP 101-3. The STA multi-link device 102includes two affiliated STAs: a STA 102-1 and a STA 102-2. The STAmulti-link device 103 includes two affiliated STAs: a STA 103-1 and aSTA 103-2. A STA 103-3 and the STA 104 each are a single-link device.The AP multi-link device may separately communicate with the STAmulti-link device 102 on a link 1 and a link 3, communicate with the STAmulti-link device 103 on a link 2 and a link 3, and communicate with theSTA 104 on a link 1. For example, the STA 104 operates on a 2.4 GHzfrequency band. The STA multi-link device 103 includes the STA 103-1 andthe STA 103-2, where the STA 103-1 operates on a 5 GHz frequency band,and the STA 103-2 operates on a 6 GHz frequency band. The STA multi-linkdevice 102 includes the STA 102-1 and the STA 102-2, where the STA 102-1operates on a 2.4 GHz frequency band, and the STA 102-2 operates on a 6GHz frequency band. The AP 101-1 operating on the 2.4 GHz frequency bandin the AP multi-link device may perform uplink or downlink datatransmission with the STA 104 and the STA 102-2 in the STA multi-linkdevice 102 on a link 1. The AP 101-2 operating on the 5 GHz frequencyband in the AP multi-link device may perform uplink or downlink datatransmission with the STA 103-1 operating on the 5 GHz frequency band inthe STA multi-link device 103 on a link 2. The AP 101-3 operating on the6 GHz frequency band in the AP multi-link device 101 may perform uplinkor downlink data transmission with the STA 102-2 operating on the 6 GHzfrequency band in the STA multi-link device 102 on a link 3, and mayalso perform uplink or downlink data transmission with the STA 103-2 inthe STA multi-link device on the link 3.

It should be noted that FIG. 3 a shows that the AP multi-link 101 devicesupports only two frequency bands, and FIG. 3 b only uses an example inwhich the AP multi-link device 101 supports three frequency bands (2.4GHz, 5 GHz, and 6 GHz), each frequency band corresponds to one link, andthe AP multi-link device 101 may operate on one or more of link 1, 2,and link 3 for illustration. On an AP side or a STA side, the linkherein may be further understood as a station operating on the link. Inan actual application, the AP multi-link device and the STA multi-linkdevice may further support more or fewer frequency bands, and values ofthe frequency bands are not limited to 2.4 GHz, 5 GHz, 6 GHz, and thelike. In other words, the AP multi-link device and the STA multi-linkdevice may operate on more or fewer links. This is not limited in thisembodiment of this application

For example, the multi-link device is an apparatus with a wirelesscommunication function, and the apparatus may be a device, or may be achip, a processing system, or the like installed on the device. Thedevice on which the chip or the processing system is installed mayimplement methods and functions in embodiments of this application undercontrol of the chip or the processing system. For example, themulti-link STA in embodiments of this application has a wirelesstransceiver function, may support the 802.11 series protocols, and maycommunicate with the multi-link AP, another multi-link STA, or asingle-link device. For example, the multi-link STA is any usercommunication device that allows a user to communicate with an AP andthen with the WLAN. For example, the multi-link STA may be userequipment that can access a network, for example, a tablet computer, adesktop computer, a laptop computer, a notebook computer, anultra-mobile personal computer (UMPC), a handheld computer, a netbook, apersonal digital assistant (PDA), or a mobile phone; or may be aninternet of things node in the internet of things, an in-vehiclecommunication apparatus in the internet of vehicles, or the like. Themulti-link STA may alternatively be a chip or a processing system in theforegoing terminals. The multi-link AP in embodiments of thisapplication is an apparatus that provides a service to the multi-linkSTA, and can support the 802.11 series protocols. For example, themulti-link AP may be a communication entity such as a communicationserver, a router, a switch, or a network bridge, or the multi-link APmay include various forms of macro base stations, micro base stations,relay stations, or the like. Certainly, the multi-link AP may further bea chip and a processing system in the various forms of devices, toimplement the methods and functions of embodiments of this application.In addition, the multi-link device may support high-rate and low-latencytransmission. With continuous evolution of wireless local area networkapplication scenarios, the multi-link device may be further applied tomore scenarios, for example, serving as a sensor node (for example, asmart water meter, a smart electricity meter, or a smart air detectionnode) in smart city, a smart device (for example, a smart camera, aprojector, a display screen, a television, a stereo, a refrigerator, ora washing machine) in smart home, a node in internet of things, anentertainment terminal (for example, AR, VR, or another wearabledevice), a smart device (for example, a printer, or a projector) insmart office, an internet of vehicles device in internet of vehicles, orinfrastructure (for example, a vending machine, a self-servicenavigation console, a self-checkout device, or a self-service foodmachine) in daily life scenarios. Specific forms of the multi-link STAand the multi-link AP are not specifically limited in embodiments ofthis application, and are merely examples for description herein. The802.11 series protocols may include 802.11be, 802.11ax,802.11a/b/g/n/ac, and the like.

2. A Multiple Basic Service Set Identifier (BSSID) Mode

A multiple BSSID set is a combination of some collaborative orcooperative APs, and all the cooperative APs share one operating class,one channel number, and one antenna port. In the multiple BSSID set,there is only one transmitted BSSID AP, and other APs are nontransmittedBSSID APs. Information about the multiple BSSID set (that is, a multipleBSSID element) is carried in a beacon frame, a probe response frame, ora neighbor report sent by the transmitted BSSID AP. Information about aBSSID of the nontransmitted BSSID AP is derived based on a multipleBSSID element or the like in the foregoing received beacon frame, proberesponse frame, neighbor report.

In a multiple BSSID technology, one physical AP may be virtualized intoa plurality of logical APs to form a multiple BSSID set. Eachvirtualized AP manages one BSS, and different logical APs generally havedifferent SSIDs and permission, such as a security mechanism or atransmission occasion. In the multiple BSSID set, a BSSID of an AP isconfigured as a transmitted BSSID, which is referred to as a transmittedAP, and BSSIDs of other APs are configured as nontransmitted BSSIDs,which are referred to as nontransmitted APs. Generally, a plurality ofAPs in the multiple BSSID may also be understood as a plurality ofcooperative AP devices obtained by virtualizing one AP device. Only anAP whose BSSID is a transmitted BSSID can send a management frame, forexample, a beacon frame (beacon) and a probe response frame (proberesponse). The beacon frame sent by the AP whose BSSID is thetransmitted BSSID includes a multiple BSSID element, and the APs whoseBSSID is the nontransmitted BSSID cannot send a beacon frame.Association identifiers (AID) allocated by a plurality of virtual APs tostations managed by the plurality of virtual APs share one space, thatis, the AIDs allocated to stations managed by the plurality of virtualBSSs cannot be the same.

For ease of description, an AP in a BSS identified by a transmittedBSSID in a multiple BSS set is referred to as a transmitted BSSID AP,and an AP in a BSS identified by a nontransmitted BSSID is referred toas a nontransmitted BSSID AP in the following descriptions.

In an example, as shown in Table 1, the multiple BSSID element includesan element ID, a length, a maximum BSSID indicator, and a subelement.The maximum BSSID indicator indicates that a maximum quantity of BSSIDsincluded in the foregoing multiple BSSID set is n, and an optionalsubelement includes information about each nontransmitted BSSID. Areceive end may calculate a value of each BSSID in the multiple BSSIDset based on a reference BSSID, the maximum BSSID indicator, and a BSSIDidentifier. Each BSSID includes 48 bits. A value of most significant(48−n) bits of each BSSID in the multiple BSSID set is the same as avalue of most significant (48−n) bits of the reference BSSID, and avalue of least significant n bits of each BSSID in the multiple BSSIDset is obtained by performing a modulo operation on a sum of a value ofleast significant n bits of the reference BSSID and a value of a BSSIDidentifier x by using 2n. The reference BSSID (that is, the transmittedBSSID) is carried in a BSSID field in a MAC header of a frame (forexample, a beacon frame) including the multiple BSSID element. For aspecific calculation method, refer to the 802.11-2016 standard.

TABLE 1 Multiple BSSID element Element Maximum BSSID Optional ID Lengthindicator subelement Byte 1 1 6 Variable

Table 2 may show the “optional subelement” in Table 1.

TABLE 2 Optional subelement Subelement ID Name Extensible  0Nontransmitted BSSID profile No  1-220 Reserved 221 Vendor-specificVendor-defined 222-255 Reserved

In Table 2, the nontransmitted BSSID profile includes an element orelements of one or more APs or DMG STAs having a nontransmitted BSSID,and the nontransmitted BSSID profile includes but is not limited to thefollowing elements:

1. A plurality of other elements in a beacon and a nontransmitted BSSIDcapability related element that need to be included in eachnontransmitted BSSID.

2. An SSID element and a multiple BSSID-index element:

3. An FMS descriptor element that is further included if the multipleBSSID element is carried in the beacon.

4. None of the following elements: timestamp and beacon frame intervalfields, a DSSS parameter set, an IBSS parameter set, a country, achannel switch announcement, an extended channel switch announcement, awide bandwidth channel switch, a transmit power envelope, supportedoperating classes, an IBSS DFS, ERP information, HT Capabilities, an HToperation, VHT capabilities, a VHT operation), SIG beacon compatibility(SiG Beacon Compatibility), a short beacon interval, SIG capabilities(SiG Capabilities), a SIG operation (SiG Operation (11ah)), and otherelements. These elements usually have same element values as the APcorresponding to the transmitted BSSID.

5. An optional non-inheritance element: The element is the last elementin the nontransmitted BSSID profile. The non-inheritance elementincludes IDs and element ID extensions of a series of elements that arein the nontransmitted BSSID and that cannot be inherited from thetransmitted BSSID. It should be noted that specific content of theelement is omitted herein. Specifically, as shown in Table 3, thenon-inheritance element includes an element ID, a length, an element IDextension, an element ID list, and an element ID extension list. Theelement ID extension number are present only when an element ID value is255.

TABLE 3 Non-inheritance element One or more One or more One byte Onebyte One byte bytes bytes Element ID Length Element ID Element IDElement ID extension list extension list

3. Probe Request and Response

In a single-link scenario, a non-AP STA can initiate active scanning todiscover an AP, so that the STA can select an appropriate AP toassociate with.

Specifically, the non-AP STA may send a probe request frame. Afterreceiving the probe request frame, an AP may reply with a probe responseframe. The probe response frame carries related information of the AP,so that the non-AP STA can probe the AP and obtain various communicationparameters of the AP.

The probe request frame may be broadcast, that is, all APs reply with aprobe response frame after receiving the probe request frame.Alternatively, the probe request frame may be unicast, that is, theprobe request frame is sent to a specific AP, and only the specific APreplies with a probe response frame after receiving the probe requestframe.

In a scenario in which a non-AP STA supports a single link or a non-APSTA MLD and an AP MLD support a single link, to establish a multi-linktransmission channel with the AP MLD, a logical non-AP STA (hereinafterreferred to as a non-AP STA) of the non-AP STA or the non-AP STA MLDestablishes a multi-link transmission channel with the AP MLD. This canalso be implemented through active scanning.

For a device that supports both multi-link and MBSSID, there may anMBSSID set on each link. APs belonging to a same MBSSID set areclassified into APs with nontransmitted BSSIDs and APs with transmittedBSSIDs. APs of transmitted BSSIDs in different MBSSID sets are notnecessarily located in a same AP MLD.

For example, as shown in FIG. 4 :

An AP MLD 1 includes three logical APs, denoted as an AP11, an AP21, andan AP31, where the AP11, the AP21, and the AP31 respectively operate ona link 1 (link1), a link 2 (link2), and a link 3 (link3). An AP MLD 2includes two logical APs, denoted as an AP 12 and an AP 22, where the AP12 and the AP 22 respectively operate on the link 1 and the link 2. AnAP MLD 3 includes two logical APs, denoted as an AP 23 and an AP 33,where the AP 23 and the AP 33 respectively operate on the link 2 and thelink 3.

The AP MLD 1 is used as an example. MAC addresses of the AP 21 and theAP 31 are BSSID_11, BSSID_21, and BSSID_31 respectively (Before802.11ax, a BSSID of a BSS established by an AP is a MAC address of theAP, and may change subsequently. For ease of description herein, the MACaddress of the AP is used as the BSSID of the BSS established by theAP).

The AP 11 is a member in a multiple BSSID set 1, and the multiple BSSIDset 1 further includes the AP 12 whose MAC address is BSSID_12 in the APMLD 2.

The AP 21 is a member in a multiple BSSID set 2, and the multiple BSSIDset 2 further includes the AP 22 whose MAC address is BSSID_22 in the APMLD 2 and the AP 23 whose MAC address is BSSID_23 in the AP MLD 3.

The AP 31 is a member in a multiple BSSID set 3, and the multiple BSSIDset 3 further includes the AP 33 whose MAC address is BSSID_33 in the APMLD 3.

In a configuration manner, the AP 11 in the MSSID set 1 is configured asa transmitted BSSID, and the AP 12 is configured as a nontransmittedBSSID. The AP 21 in the MSSID set 2 is configured as a transmittedBSSID, and the AP 22 and the AP 23 are configured as nontransmittedBSSIDs. The AP 33 in the MSSID set 3 is configured as a transmittedBSSID, and the AP 31 is configured as a nontransmitted BSSID. It can belearned that the AP 33, the AP 11, and the AP 21 configured astransmitted BSSIDs do not belong to a same AP MLD.

This embodiment of this application further relates to a collocated APMLD or a collocated AP, which means that virtual APs belonging to a samephysical AP form a collocated AP, or virtual AP MLDs form a collocatedAP MLD.

For example, although the AP11 and the AP23 do not belong to a sameMBSSID set, the AP11 and the AP23 physically belong to a same physicalAP. The AP11 and the AP23 are considered as collocated, and the AP MLD 1in which the AP11 is located and the AP MLD 3 in which the AP23 islocated are collocated. As shown in the figure, all APs, or the AP MLD1, the AP MLD 2, and the AP MLD 3 can be collocated.

In this embodiment of this application, a probing and respondingmechanism between a non-AP STA and one or more AP MLDs is proposed.Logical APs in the plurality of AP MLDs may belong to a same MSSID, ormay belong to different MSSIDs.

In a first case, if the non-AP STA wants to obtain a communicationparameter of an AP MLD in which an AP with the nontransmitted BSSID islocated, the non-AP STA may send a probe request frame to an AP with anontransmitted BSSID in an MBSSID set. In this case, in the MBSSID set,the AP with the transmitted BSSID needs to reply with a probe responseframe.

In other words, if a nontransmitted BSSID AP in the MBSSID set receivesthe probe request frame from the non-AP STA or the non-AP STA MLD, thecommunication parameter of the nontransmitted BSSID AP may be replied tothe non-AP STA or the non-AP STA MLD by using the transmitted BSSID AP.The AP of the nontransmitted BSSID and the AP of the transmitted BSSIDmay belong to different AP MLDs.

In a second case, if the non-AP STA wants to probe a plurality of APMLDs at a time, the non-AP STA or the non-AP STA MLD may send a proberequest frame to an AP of a transmitted BSSID, to request the AP of thetransmitted BSSID to reply with a communication parameter of thenontransmitted BSSID AP. The AP of the nontransmitted BSSID and the APof the transmitted BSSID may belong to different AP MLDs. When there area plurality of APs of the nontransmitted BSSID, the APs of the multiplenontransmitted BSSIDs may also belong to different AP MLDs.

In other words, if a transmitted BSSID AP receives the probe requestframe from the non-AP STA or the non-AP STA MLD, the transmitted BSSIDAP may reply with communication parameters of other nontransmitted BSSIDAPs in the multiple BSSID set together with or separately to the non-APSTA by using a probe response frame. Alternatively, the transmittedBSSID AP may reply with a communication parameter of anothernontransmitted BSSID AP in the multiple BSSID set, and a communicationparameter of an AP MLD in which another AP is located to the non-AP STAtogether with or separately by using the probe response frame, where theanother AP is collocated with the transmitted BSSID AP.

In the foregoing two cases, the non-AP STA may carry indicationinformation in the probe request frame, to indicate the communicationparameter that the non-AP STA expects to receive from the AP MLD, or mayrequest, in a default manner, the AP MLD to reply with all communicationparameters.

4. An MLD Communication Parameter of an AP

In this embodiment, a communication parameter of an AP MLD isinformation used by a non-AP STA or a non-AP STA MLD to subsequentlyassociate with the AP MLD or information used to establish multi-linkcommunication. The communication parameter of the AP MLD in thisembodiment of this application may be communication parameterscorresponding to all links supported by the AP MLD, or may becommunication parameters corresponding to some links supported by the APMLD.

In this embodiment, the communication parameter of the AP MLD is alsoreferred to as an association parameter of the AP MLD or completeinformation of the AP MLD, and refers to complete information of aplurality of links included in the MLD. For each link, the completeinformation of the link is information that should be carried only whenthe probe response frame is sent on the link.

Specifically, the communication parameter may include a capabilityinformation element, an operation information element, and otherinformation elements, for example, an enhanced distributed channelaccess parameter set (enhanced distributed channel access, EDCA), highthroughput capabilities (HT capabilities), an HT operation, very highthroughput capabilities (VHT capabilities), a VHT operation, highefficiency capabilities (HE capabilities), a high efficiency operation(HE operation), extremely high throughput capabilities (extremely highthroughput, EHT capabilities), and an EHT operation.

When a frequency band on which a link is located is 6 GHz, thecommunication parameter may not include the high throughput capabilities(HT capabilities), the HT operation, the very high throughputcapabilities (VHT capabilities), or the VHT operation.

Optionally, the communication parameter further includes:

elements such as timestamp and a beacon frame interval fields (timestampand Beacon interval fields), a DSSS parameter set, an IBSS parameterset, a country, a channel switch announcement, an extended channelswitch announcement, a wide bandwidth channel switch, a transmit powerenvelope, supported operating classes, IBSS DFS, ERP information, an SIGbeacon compatibility (SiG beacon compatibility), a short beaconinterval, SIG capabilities (SiG capabilities), and an SIG operation (SiGoperation (11ah)).

In an optional embodiment, for the communication parameter of the MLDcarried in the probe response frame, only a communication parameter of alink supported by the non-AP MLD may be carried, and for a link notsupported by the non-AP MLD, a corresponding communication parameter maynot be carried. A non-AP can negotiate with an AP MLD about supportedand unsupported links in advance.

By default, the probe response frame needs to carry communicationparameters of all links supported by the AP MLD. Certainly, in someimplementations, the probe response frame may carry communicationparameters of only some links supported by the AP MLD.

In this embodiment of this application, a communication parameter of alink of an AP MLD may also be referred to as a communication parameterof an AP corresponding to the link.

The following describes an implementation process of this application indetail by using embodiments.

Embodiment 1

FIG. 5 shows a probing method based on a multi-link device and an MBSSIDaccording to an embodiment of this application. The method may beapplied between stations, between an access point and a station, andbetween access points. For ease of description, communication between anaccess point and a station is used as an example in this embodiment ofthis application. There are a plurality of links between the accesspoint and the station.

First, a scenario of this embodiment is described. In the scenario, aplurality of AP MLDs are included, for example, a first AP MLD and asecond AP MLD. A logical AP of the first AP MLD is a first AP, and isconfigured as a nontransmitted BSSID. A logical AP of the second AP MLDis referred to as a second AP, and is configured as a transmitted BSSID.The first AP and the second AP may operate on a same link and belong toa same MBSSID set. In this scenario, a non-AP STA (which may be asingle-link non-AP STA or a logical non-AP STA in a non-AP STA MLD,which is not limited in this application) obtains a communicationparameter of the first AP MLD by using a nontransmitted BSSID AP, toestablish a multi-link channel with the first AP MLD. In addition, aplurality of APs or the plurality of AP MLDs in this scenario may becollocated.

A communication parameter of the AP MLD is described in detail in theforegoing fourth point, and details are not described in this embodimentagain.

The method includes but is not limited to the following steps.

Step S101: A non-AP STA sends a probe request frame to a first AP over afirst link in a plurality of links between the non-AP STA and a first APMLD.

In an explicit indication manner, the probe request frame carries firstindication information, and the first indication information is used torequest a communication parameter of the first AP MLD.

In an implicit indication manner, the probe request frame does not carrythe first indication information. In other words, the communicationparameter of the first AP MLD is requested by default in the implicitindication manner.

Because the first AP is configured as a nontransmitted BSSID, that is,the first AP is a nontransmitted BSSID AP, the first AP cannot directlyreply with a probe request response frame to the non-AP STA. Therefore,a second AP that is configured as a transmitted BSSID and that belongsto a same MBSSID set may help the first AP respond to the probe requestframe.

Step S102: The second AP replies with the probe response frame to thenon-AP STA, where the probe response frame carries the communicationparameter of the first AP MLD. Specifically, for the foregoing explicitindication manner or implicit indication manner, the second AP replieswith the probe response frame in the non-AP STA, where the proberesponse frame carries the communication parameter of the first AP MLD.

During implementation of this embodiment of this application, when thenon-AP STA wants to request a communication parameter of an AP MLD, thenon-AP STA may send a probe request frame to a logical AP of the AP MLD.Even if the logical AP is configured as a nontransmitted BSSID, anothertransmitted BSSID AP belonging to a same MSSID set may respond to theprobe request frame, to reply with the communication parameter of the APMLD. This can resolve a technical problem in the conventional technologythat a communication parameter of an AP MLD on another link cannot beobtained by sending the probe request frame.

For example, in FIG. 4 , a non-AP STA wants to learn a communicationparameter of an AP MLD 2, to establish a multi-link communicationconnection to the AP MLD 2. Specifically, the non-AP STA wants to obtaina communication parameter corresponding to a link 1 of the AP MLD 2 anda communication parameter corresponding to a link 2. The non-AP STAsends a probe request frame to an AP 12, where the probe request framerequests, by default, the AP 12 to reply with a communication parameterof the AP MLD 2 in which AP12 is located. Alternatively, the firstindication information is carried in the probe request frame, and thefirst indication information indicates the AP 12 to reply with thecommunication parameter of the AP MLD 2 in which AP12 is located.

Because a BSSID of the AP 12 is configured as the nontransmitted BSSID,the AP 12 cannot directly reply to the non-AP STA. Therefore, the AP 12responds to the probe request frame by using the AP 11 that belongs to asame MSSID set 1 as the AP 12. (A BSSID of the AP 11 is configured as atransmitted BSSID.)

The AP 11 carries, in the probe response frame replied to the non-APSTA, the communication parameters of the plurality of links supported bythe AP MLD 2. The plurality of links supported by the AP MLD 2 hereinmay be all links supported by the AP MLD 2, for example, the link 1 andthe link 2, or may be some links supported by the AP MLD 2.

Embodiment 2

FIG. 6 shows a probing method based on a multi-link device and an MBSSIDaccording to an embodiment of this application. The method may beapplied between stations, between an access point and a station, andbetween access points. For ease of description, communication between anaccess point and a station is used as an example in this embodiment ofthis application. There are a plurality of links between the accesspoint and the station.

First, an implementation scenario of this embodiment is similar to thatof Embodiment 1, and details are not described herein again. Adifference from Embodiment 1 in that, in Embodiment 2, a non-AP STAwants to obtain a communication parameter of one or more AP MLD by usinga transmitted BSSID AP, to separately establish a multi-link channelwith the one or more MLDs.

For the communication parameter of the AP MLD in Embodiment 2, refer tothe foregoing fourth point. Details are not described again in thisembodiment.

The method includes but is not limited to the following steps.

Step S201: A non-AP STA sends a probe request frame to a second AP overa first link in a plurality of links between the non-AP STA and a firstAP MLD. The probe request frame is used to request the second AP tocarry a communication parameter of an MLD in a probe response frame.

Because the second AP is configured as a transmitted BSSID, that is, thesecond AP is a transmitted BSSID AP, the second AP may directly replywith a probe request response frame to the non-AP STA.

In an implicit indication manner, a default function of the proberequest frame may be as follows.

(1) A default function of the probe request frame is to request acommunication parameter of a receiving object of the probe requestframe, that is, a communication parameter of a second AP MLD in whichthe second AP is located. The second AP considers by default that theprobe request frame is used to request the communication parameter ofthe second AP MLD in which the second AP is located.

(2) A second default function of the probe request frame is: The proberequest frame is used to request a communication parameter of anotherMLD other than the second AP MLD in which the second AP is located.

(3) A third default function of the probe request frame is: The proberequest frame is used to request a communication parameter of the secondAP MLD in which the second AP is located and a communication parameterof another MLD.

Which function in the foregoing three functions is used by the proberequest frame by default may be agreed on in a protocol, or may beagreed on between the non-AP STA and the requested AP.

In another explicit indication manner, the probe request frame mayfurther carry second indication information, and the second indicationinformation is used to request a communication parameter on a pluralityof links included in an MLD corresponding to the second indicationinformation, that is, request the second AP to carry, in a probe requestresponse frame replied to the non-AP STA, a communication parameter ofthe plurality of links included in the MLD. Similar to the foregoingimplicit indication manner, when the second indication information maybe used to request a communication parameter of an AP MLD, the followingthree cases are also included:

a communication parameter of an AP MLD in which the second AP is locatedis requested;

a communication parameter of another AP MLD other than the AP MLD inwhich the second AP is located is requested; and

a communication parameter of an AP MLD in which the second AP is locatedand a communication parameter of another AP MLD are requested.

It should be noted that the “another AP MLD” involved in the foregoingimplicit and/or explicit indication manners refers to an AP MLD otherthan an AP MLD in which the AP is located, or an AP MLD other than theMLD in which the local AP is located, for example, an AP MLD in whichanother AP belonging to a same MBSSID as the second AP is located,and/or an AP MLD in which another AP sharing a same address with thesecond AP is located.

In an implementation, the “another MLD” may be an AP MLD in which thesecond AP is located and another AP MLD in the same MBSSID set to whichthe second AP belongs.

In an implementation, the “another MLD” may be an AP MLD that iscollocated with the second AP except the AP MLD in which the second APis located.

In an implementation, the “another MLD” may be another AP MLD, exceptthe AP MLD in which the second AP is located, in which another APbelonging to the same MBSSID set as the second AP is located, and an APMLD that is collocated with the second AP.

The second indication information requests a communication parameter ofthe another AP MLD. The second indication information may be set to 1bit, to indicate that the AP MLD in which the second AP is located andthe communication parameter of the another AP MLD are requested. Thesecond indication information may be represented as a field “all MLDrequired”.

The “another MLD” herein may be an MLD in which another nontransmittedBSSID AP belonging to the same MBSSID set as the second AP is located,and an AP MLD in which another AP collocated with the second AP islocated.

The second indication information may be set to 1 bit, to indicate thata communication parameter of another AP MLD is requested. The secondindication information may be represented as a field “other MLDrequired”.

In another implementation, the “another MLD” may be an MLD in whichanother nontransmitted BSSID AP belonging to the same MBSSID set as thesecond AP is located. The second indication information may be set to 1bit, to indicate that a communication parameter of an AP MLD in whichthe nontransmitted BSSID AP is located is requested. The secondindication information may be represented as a field “all nontransmittedMLD required”.

In still another implementation, the “another MLD” may be one or morespecific MLDs. In this case, the second indication information iscarried in the probe request frame, and the second indicationinformation indicates identifiers (ID) or MLD addresses of one or moreMLDs. Herein, the MLD identifier may be an MLD MAC address, an MLDindex, an MLD ID, or a BSSID index.

It should be noted that, the MLD MAC Address represents a MAC SAPaddress of the MLD, which is usually 48 bits. A length of the MLD ID isshort, which is less than 48 bits, for example, 8 bits or 4 bits.BSSID-index represents a sequence number of a virtual AP in the MBSSIDset in which the second AP is located.

In yet another implementation, the non-AP STA may set the secondindication information carried in the probe request frame to differentvalues, to request communication parameters of different AP MLDs.

For example, the second indication information is set to a first value,to indicate that only a communication parameter of the AP MLD in whichthe second AP is located is requested. For example, the second AP is anAP 21, and an AP MLD in which the AP 21 is located is an AP MLD 1.

For another example, the second indication information is set to asecond value, which indicates requesting communication parameters of theAP MLD in which the second AP is located and the AP MLD in which thenontransmitted BSSID AP that belongs to the same MBSSID set as thesecond AP is located. For example, the second AP is the AP 21, the AP21, an AP 22, and an AP 23 belong to a same MBSSID set 2, and the AP 22and the AP 23 are configured as nontransmitted BSSIDs. Therefore, thesecond value represents requesting communication parameters of the APMLD 1 in which the AP 21 is located, an AP MLD 2 in which the AP 22 islocated, and an AP MLD 3 in which the AP 23 is located.

For another example, the second indication information is set to a thirdvalue, which indicates requesting a communication parameter of the APMLD in which the second AP is located and a communication parameter ofthe AP MLD in which the nontransmitted BSSID AP that belongs to the sameMBSSID set as the second AP is located, and/or requesting acommunication parameter of an AP MLD in which an AP collocated with thesecond AP is located. For example, the second AP is the AP 21, all APMLDs are the AP 21 and AP MLDs in which the AP 22 and the AP23 thatbelongs to a same MBSSID set 2 as the AP 21 are respectively located,that is the AP MLD 1 in which the AP 21 is located, the AP MLD 2 inwhich the AP22 is located, and the AP MLD 3 in which the AP23 islocated. All AP MLDs further include an AP MLD (not shown in the figure)where an AP that does not belong to a same MBSSID set as the AP21 but iscollocated with the AP21 is located (not shown in the figure).

The second indication information may alternatively be set to anothervalue, to indicate a status of a requested communication parameter ofthe AP MLD.

Step S202: The second AP replies with the probe response frame to thenon-AP STA, where the probe response frame carries the communicationparameter of the AP MLD.

In the foregoing implicit indication manner, when the second AP receivesthe probe request frame, that is, a function of the probe request frameis one of the foregoing three default functions, the second AP repliesto the probe response frame based on a protocol agreement or anagreement with the non-AP STA. Details are as follows.

(1) For the first default function, the second AP may reply with theprobe response frame to the non-AP STA, to carry a communicationparameter of the second AP MLD in which the second AP is located.

(2) For the second default function, the second AP may reply with theprobe response frame to the non-AP STA by default, to carry acommunication parameter of an MLD other than the second AP MLD in whichthe second AP is located.

(3) The second AP may reply with the probe response frame to the non-APSTA by default, to carry a communication parameter of the second AP MLDin which the second AP is located and a communication parameter ofanother MLD.

For the foregoing explicit indication manner, when receiving the proberequest frame carrying the second indication information, the second APreplies with a corresponding probe response frame based on an indicationof the second indication information.

Specifically, the second AP receives the second indication information,parses an MLD identifier carried in the second indication information,and replies with, in the probe response frame, a communication parametercorresponding to the MLD identifier to the non-AP STA.

In an implementation, for the communication parameters of the MLDs ofall the other APs that are requested by using the second indicationinformation, the second AP replies with a probe response frame to thenon-AP STA in the probe response frame, where the probe response framecarries the communication parameters of the MLDs of all the other APs.

In another implementation, when the second indication informationrequests a communication parameter of an MLD in which anothernontransmitted BSSID AP is located, the second AP replies with the proberesponse frame to the non-AP STA in the probe response frame, and theprobe response frame carries a communication parameter of an MLD inwhich another nontransmitted BSSID AP is located.

In still another implementation, when the second indication informationrequests one or more specific MLDs, the second AP replies with a proberesponse frame to the non-AP STA in the probe response frame, where theprobe response frame carries a communication parameter of the MLDcorresponding to the MLD identifier indicated by the second indicationinformation.

In yet another implementation, the second indication information mayalso be set to different values, to indicate that when communicationparameters of different AP MLDs are requested, the second AP replieswith the probe response frame to the non-AP STA in the probe responseframe, where the probe response frame carries the communicationparameter of the MLD requested by the second indication information.

For example, for the second indication information that is set to afirst value, the second AP feeds back, by using the probe responseframe, the communication parameter of the AP MLD in which the second APis located. For example, the second AP is the AP 21, and the AP 21 feedsback a communication parameter of an AP MLD in which the AP 21 islocated, that is, the AP MLD 1.

For another example, for the second indication information that is setto a second value, the second AP feeds back, by using the probe responseframe, the AP MLD in which the second AP is located and thecommunication parameter of the AP MLD in which the nontransmitted BSSIDAP that belongs to the same MBSSID set as the second AP is located. Forexample, the second AP is the AP 21, the AP 21, the AP 22, and the AP 23belong to the same MBSSID set 2, and the AP 22 and the AP 23 areconfigured as nontransmitted BSSIDs. Therefore, the AP 21 feeds backcommunication parameters of the AP MLD 1 in which the AP 21 is located,the AP MLD 2 in which the AP 22 is located, and the AP MLD 3 in whichthe AP 23 is located.

For another example, the second indication information is set to a thirdvalue, and the second AP feeds back communication parameters of all APMLDs by using the probe response frame. For example, the second AP isthe AP 21, and all the AP MLDs are the AP 21 and AP MLDs in which the AP22 and the AP 23 that belongs to a same MBSSID set 2 as the AP 21 arerespectively located. In other words, the AP 21 feeds back communicationparameters of the AP MLD 1 in which the AP 23 is located, the AP MLD 2in which the AP 22 is located, and the AP MLD 3 in which the AP 23 islocated.

During implementation of this embodiment of this application, when anon-AP STA wants to request a communication parameter of an AP MLD, thenon-AP STA may send a probe request frame to an AP configured as atransmitted BSSID AP. The transmitted BSSID AP may reply a communicationparameter of an MLD in which another AP belonging to a same MSSID set islocated and/or a communication parameter of an MLD in which another APcollocated with the transmitted BSSID AP is located. Therefore, atechnical problem in the conventional technology that the MLDcommunication parameter of the another AP cannot be obtained by sendingthe probe request frame is resolved.

Similarly, for example in FIG. 4 , a non-AP STA wants to learncommunication parameters of one or more AP MLDs, to establish amulti-link communication connection. For example, the AP21 in the MSSIDset 2 is configured as a transmitted BSSID, and the AP22 and the AP23are configured as nontransmitted BSSIDs.

In a first case, if the non-AP STA wants to obtain the communicationparameter of the AP MLD 1 in which the AP 21 is located, the non-AP STAsends the probe request frame to the AP 21, where the probe requestframe is used to request, by default, the communication parameter of theAP MLD 1 in which the AP 21 is located, or carries the second indicationinformation, which indicates that the communication parameter of the APMLD 1 in which the AP 21 is located is requested. Because a BSSID of theAP 21 is configured as a transmitted BSSID, the AP 21 may directly replywith the probe response frame, and carry the communication parameter ofthe AP MLD 1 in the probe response frame. Specifically, thecommunication parameter of the AP MLD 1 may be communication parametersof a link 1, a link 2, and a link 3 supported by the AP MLD 1, or may becommunication parameters of all or some links supported by the non-APSTA.

In a second case, the non-AP STA wants to obtain a communicationparameter of an AP MLD other than the AP MLD 1 in which the AP 21 islocated, for example, wants to obtain a communication parameter of theAP MLD 2 and/or the AP MLD 3. The non-AP STA sends the probe requestframe to the AP 21, where the probe request frame is used to request, bydefault, a communication parameter of an MLD other than the AP MLD 1 inwhich the AP 21 is located, or carries the second indicationinformation, to indicate to request the communication parameter of theMLD other than the AP MLD 1 in which the AP 21 is located. Because theBSSID of the AP 21 is configured as the transmitted BSSID, the AP 21 maydirectly reply with the probe response frame, and carry, in the proberesponse frame, the communication parameter of the MLD other than the APMLD 1 in which the AP 21 is located. For example, an MLD identifierindicated by the second indication information is the AP MLD 2 and theAP MLD 3. Alternatively, if the second indication information is “allMLD required”, the AP 21 carries communication parameters of the AP MLD2 and the AP MLD 3 in the probe request response frame. For anotherexample, if the second indication information is “allnontransmitted MLDrequired”, the AP 21 carries the communication parameters of the AP MLD2 and the AP MLD 3 in the probe request response frame. For anotherexample, if the MLD identifier indicated by the second indicationinformation is the AP MLD 2, the AP 21 carries the communicationparameter of the AP MLD 2 in the probe request response frame.

In a third case, the non-AP STA wants to obtain communication parametersof the AP MLD 1 in which the AP 21 is located and another AP MLD, forexample, wants to obtain communication parameters of all or some MLDs ofthe AP MLD 1, the AP MLD 2, and the AP MLD 3. The non-AP STA sends theprobe request frame to the AP 21, where the probe request frame is usedto request, by default, communication parameters of the AP MLD 1 inwhich the AP 21 is located and another MLD, or carries the secondindication information, to indicate to request the communicationparameters of the AP MLD 1 in which the AP 21 is located and the anotherMLD. Because the BSSID of the AP 21 is configured as the transmittedBSSID, the AP 21 may directly reply with a probe response frame, andcarries, in the probe response frame, the AP MLD 1 in which the AP 21 islocated and the communication parameter of the another MLD.Specifically, similar to the foregoing description, the AP 21 may carrycommunication parameters of the AP MLD 1, the AP MLD 2 and/or the AP MLD3 in the probe response frame based on the indication of the secondindication information.

The AP 21 carries, in the probe response frame replied to the non-APSTA, the communication parameters of the plurality of links supported bythe one or more AP MLDs.

Embodiment 3

This embodiment of this application further describes several elementsthat are in a probe request frame and that are used to implement AP MLDprobe request. The element may carry the first indication information inEmbodiment 1, or carry the second indication information in Embodiment2. Embodiment 3 further describes an element that is in a probe responseframe and that is used to carry a communication parameter of an AP MLD.

A probe request frame in this embodiment includes a plurality of typesof the following fields:

TABLE 4 No. Information 1 HT capabilities (HT capabilities) 2 VHTcapabilities (VHT capabilities). This field does not exist when afrequency band is 6 GHz. 3 HE capabilities (HE capabilities) 4 EHTcapabilities (EHT capabilities) 5 Known BSSID (known BSSID) 6 HE 6 GHzfrequency band capabilities (HE 6 GHz band capabilities) 7 Short SSIDlist (short SSID list) 8 Requested MLD element (requested MLD element) 9Multi-link element (multi-link element) 10 Known MLD element (known MLDelement) 11 MLD address or MLD identifier (MLD address or MLD ID) 12BSSID index bitmap (BSSID index bitmap)

In the explicit indication manner in the foregoing embodiment, the firstindication information and the second indication information may beimplemented in various forms. For example, the first indicationinformation and the second indication information may be carried in theprobe request frame as separate elements, for example, a multi-linkelement and a requested MLD element. Alternatively, a known MLD elementmay be carried in the probe request frame in a form of an MLD address,an MLD identifier, or a BSSID index bitmap for indication. This isdescribed in detail below.

(1) First, a specific implementation of a signaling structure of themulti-link element is described. The multi-link element may be used inthe foregoing Embodiment 1 and Embodiment 2.

According to a flexible signaling structure provided in this embodiment,a probe request frame sent by a non-AP STA carries the multi-linkelement, to request a communication parameter of an AP MLD.Alternatively, one or more multi-link elements are carried in the proberequest frame sent by the non-AP STA, to request communicationparameters of a plurality of AP MLDs. Specifically, one piece ofindication information may be carried in one multi-link element torequest the communication parameters of the plurality of AP MLDs, or aplurality of pieces of indication information may be respectivelycarried in a plurality of multi-link elements to request thecommunication parameters of the plurality of AP MLDs. In anotherimplementation, one multi-link element (carrying no indicationinformation) may be used to request the communication parameters of theplurality of AP MLDs, or a plurality of multi-link elements (carrying noindication information) may be used to request the communicationparameters of the plurality of AP MLDs

FIG. 7 a is a schematic diagram of a structure of a multi-link element.The multi-link element includes an element identifier, a length, anelement identifier extension field, a common control field, an MLDcommon information field, and one or more optional subelements. Thecommon control field includes a virtual MLD field and a special MLDfield. Optionally, the common control field further includes an MLDaddress present field. The MLD common information field includes an MLDaddress field. Optionally, the common control field further includes anauthentication algorithm present field, to indicate whether there is anauthentication algorithm field in the MLD common information field.

FIG. 7 b is a schematic diagram of a structure of another multi-linkelement. The multi-link element includes an element identifier, alength, an element identifier extension field, a common control field,an MLD common information field, and one or more optional subelements.The common control field includes an MLD type indication. Optionally,the MLD common control field further includes an MLD address presentfield. The MLD common information field includes an MLD address field.Optionally, the common control field further includes an authenticationalgorithm present field, to indicate whether there is an authenticationalgorithm field in the MLD common information field.

FIG. 7 c is a schematic diagram of a structure of still anothermulti-link element. The multi-link element includes an elementidentifier, a length, an element identifier extension field, a commoncontrol field, an MLD common information field, and one or more optionalsubelements. The common control field includes an MLD address presentfield. The MLD common information field includes an MLD address field.Optionally, the common control field further includes an authenticationalgorithm present field, to indicate whether there is an authenticationalgorithm field in the MLD common information field.

FIG. 7 d is a schematic diagram of a structure of yet another multi-linkelement. The multi-link element includes an element identifier, alength, an element identifier extension field, a common control field,an MLD common information field, and one or more optional subelements.The MLD common information field includes an MLD address field.

Each of the foregoing four possible structures of the multi-link elementincludes one or more optional subelements, and one optional subelementdescribes information about one AP in the AP MLD. The optionalsubelement may be referred to as a link configuration element linkprofile element or a link profile subelement link profile subelement,and the link profile subelement or the link profile element carries acommunication parameter of an AP. Alternatively, the link profilesubelement or the link profile element carries a communication parameterof a link.

In this embodiment of this application, the link profile subelement orthe link profile element carried in the probe request frame indicatesthe communication parameter of the AP or the link that requests an APMLD. The link profile subelement or the link profile element carried inthe probe response frame is used to carry the communication parameter ofthe AP of the AP MLD or the link.

When the multi-link element does not carry the link profile subelementor the link profile element, it indicates, by default, thatcommunication parameters of all APs or all links in the entire AP MLDare requested or responded to.

It should be understood that the foregoing four structures of themulti-link element are merely examples. A field or a subfield in themulti-link element may be deleted or added, and a name of the multi-linkelement may be another synonym name. In a standard formulation ortechnical development process, another structure may further exist. Thisis not limited in this application.

As shown in FIG. 8 , content of each optional subelement includes a linkidentifier of an AP. Optionally, each optional subelement furtherincludes an AP-related field, for example, an SSID field, a timestampfield, a beacon interval field, and an element of the AP. The element ofthe AP is, for example, a BSS load element, an EHT capability element,or an EHT operation element.

In Embodiment 1, the explicit indication manner is used. When a non-APSTA wants to request a communication parameter of a first AP MLD, thenon-AP STA may send a probe request frame to a logical AP of the firstAP MLD, where the logical AP is configured as a nontransmitted BSSID.The non-AP STA may carry first indication information in the proberequest frame, where the first indication information is used to requestthe communication parameter of the first AP MLD. The first indicationinformation may be an “MLD complete information required in proberesponse (MLD complete info required in probe response) field.

In an implementation, as shown in FIG. 9 a , the multi-link elementincludes fields such as an element ID, a length, an element IDextension, a control, and multi-link device common information (MLDcommon info), and a link profile subelement. The multi-link devicecommon information field includes the “MLD complete info required inprobe response” field. It should be noted that the field name herein isonly an example, and another name may be used during standardformulation or product implementation.

The “MLD complete info required in probe response” may be indicated byusing one bit, for example, 1 indicates a request is made, and 0indicates no request is made.

In this embodiment, an example in which the field may be carried in anMLD common information field of the multi-link element is used fordescription. In another implementation, the field may alternatively becarried in another field, for example, a control field. Details are notdescribed herein.

In addition, in another implementation, the MLD complete info requiredin probe response field may be further carried in any multi-link elementshown in 7 a to 7 d. A function of the multi-link element is similar tothat of 9 a, and details are not described herein again.

In another implementation, as shown in FIG. 9 b , the multi-link elementincludes fields such as an element ID, a length, an element IDextension, a control, and multi-link device common information (MLDcommon info), and a link profile subelement. The multi-link devicecommon information field includes the “MLD address or MLD identifier”field. It should be noted that the field name herein is only an example,and another name may be used during standard formulation or productimplementation.

The “MLD address or MLD identifier” indicates the AP MLD requested bythe non-AP STA, and the link profile subelement indicates a link of therequested AP MLD. An AP responsible for responding to the probe requestframe replies to the AP MLD corresponding to the “MLD address or MLDidentifier”, and replies with the communication parameter of the linkcorresponding to the link profile subelement.

In Embodiment 2, an explicit indication manner is used.

In one case, when a non-AP STA requests only a communication parameterof an AP MLD in which a second AP is located, a probe request framecarries second indication information, and the second indicationinformation may be carried in the multi-link element shown in FIG. 7 ato FIG. 7 c . Specifically, an MLD address in the multi-link element maybe set to an address of the AP MLD in which the second AP is located,indicating that the second indication information requests acommunication parameter of the AP MLD in which the second AP is located.

In still another case, the non-AP STA requests a communication parameterof another AP MLD other than the second AP MLD in which the second AP islocated, and the probe request frame may carry THE second indicationinformation, which is specifically a multi-link element.

The multi-link element may be shown in FIG. 9 c . An “other MLDrequired” field included in the multi-link element indicates whether torequest the communication parameter of the another MLD other than thesecond AP MLD in which the second AP is located. The second AP thatreceives the probe request frame feeds back, by default, to a non-APMLD, a communication parameter of an AP MLD other than the AP MLD inwhich the second AP is located. In this manner, another AP MLD includesan AP MLD in which another nontransmitted BSSID AP belonging to a sameMBSSID set as the second AP is located and/or an AP MLD in which anotherAP collocated with the second AP is located.

In the “other MLD required” field, 1 bit may be used to indicate whethera request is made. For example, 1 indicates that a request is made, and0 indicates that no request is made.

Alternatively, the multi-link element may be shown in FIG. 9 d . An “allnontransmitted MLD required” field included in the multi-link elementindicates, by default, that a communication parameter of an AP MLD inwhich another nontransmitted BSSID AP belonging to the same MBBID set asthe second AP is located, other than the second AP MLD of in which thesecond AP is located is requested. The second AP receiving the proberequest frame feeds back, by default, to the non-AP MLD, a communicationparameter of another nontransmitted BSSID AP MLD other than AP MLD inwhich the second AP is located. In the “all nontransmitted MLD required”field, 1 bit may be used to indicate whether a request is made. Forexample, 1 indicates that a request is made, and 0 indicates that norequest is made.

In still another case, the non-AP STA requests communication parametersof the second AP MLD in which the second AP is located and another APMLD. The probe request frame may carry the second indicationinformation, which is specifically the multi-link element. Themulti-link element may be shown in FIG. 9 e . An “all MLD required”field included in the multi-link element indicates, by default, that thecommunication parameters of the second AP MLD in which the second AP islocated and the another AP MLD are requested. The second AP receivingthe probe request frame feeds back, by default, to the non-AP MLD, thecommunication parameters of the second AP MLD in which the second AP islocated and the another AP MLD

In one manner, the “all MLD required” request includes communicationparameters of the second AP and an AP MLD in which anothernontransmitted BSSID AP belonging to a same MBSSID set as the second APis located.

In another manner, the “all MLD required” request includes communicationparameters of the second AP and an AP MLD in which another AP collocatedwith the second AP is located.

In still another manner, the “all MLD required” request includes thesecond AP and the AP MLD in which the another nontransmitted BSSID APbelonging to the same MBSSID set as the second AP is located, and the APMLD in which the another AP collocated with the second AP is located.

Similarly, the “all MLD required” may be indicated by using one bit, forexample, 1 indicates a request is made, and 0 indicates no request ismade.

When the non-AP STA requests the communication parameter of the secondAP MLD which the second AP is located and the communication parameter ofthe another MLD, an “other MLD required” field shown in FIG. 9 c may befurther used. In addition, this is implemented by setting an MLD addressor an MLD identifier in the multi-link element of the probe requestframe to an address or an identifier of the second AP.

The foregoing uses a specific field to indicate the requested AP MLD,and the multi-link element may carry an MLD address or an MLDidentifier. In this case, the MLD address or the MLD identifierindicates an address of an MLD in which the second AP receiving theprobe request frame is located.

In another case, the non-AP STA wants to obtain a communicationparameter of one or more specific AP MLDs by using the probe requestframe. In this implementation, the one or more AP MLDs may be the AP MLDin which the second AP is located, or one or more of AP MLDs in whichother APs that belong to the same MBSSID set as the second AP arelocated, or one or more of AP MLDs where other APs collocated with thesecond AP are located.

In an implementation, the second indication information is the MLDidentifier or the MLD address, and the MLD identifier or the MLD addressindicates one or more MLDs. Herein, the MLD identifier or the MLDaddress may be specifically an MLD MAC address, an MLD index, an MLD ID,or a BSSID index.

For example, the MLD identifier or the MLD address is carried in theprobe request frame (in this case, the multi-link element does not needto be carried).

For another example, the MLD identifier or the MLD address is carried inthe multi-link element in the probe request frame.

In the foregoing two manners, that the non-AP STA wants to obtain acommunication parameter of an AP MLD by using a probe request frame maybe implemented by using the probe request frame or the multi-linkelement in the probe request frame. Specifically, the probe requestframe, or the MLD address or the MLD identifier in the multi-linkelement in the probe request frame is set to an address or an identifierof the AP MLD that the probe request frame needs to request.

The non-AP STA may want to obtain communication parameters of aplurality of AP MLDs by using the probe request frame by carrying aplurality of MLD addresses or identifiers in the probe request frame, orby carrying a plurality of MLD addresses or identifiers in onemulti-link element in the probe request frame, or respectively carryinga plurality of MLD addresses or identifiers in a plurality of multi-linkelements in the probe request frame.

In another implementation, the second indication information is a BSSIDindex bitmap, and each bit of the BSSID index bitmap corresponds to oneAP MLD. A corresponding bit is set to 0 or 1 to indicate whether torequest a communication parameter of an AP MLD corresponding to thecorresponding bit.

For example, the BSSID index bitmap is carried in the probe requestframe (in this case, the multi-link element does not need to becarried).

For still another example, the BSSID index bitmap is carried in themulti-link element in the probe request frame.

In the foregoing two examples, that the non-AP STA wants to obtain acommunication parameter of an AP MLD by using the probe request framemay be implemented by using the probe request frame or the multi-linkelement in the probe request frame. Specifically, the probe requestframe or a corresponding bit in a BSSID index bitmap in the multi-linkelement in the probe request frame is set to 1 to indicate ato-be-requested AP MLD.

(2) The following describes a specific implementation of a signalingstructure of a requested MLD element. The requested MLD element may beused in the foregoing Embodiment 1 and Embodiment 2.

In this embodiment, one or more requested MLD elements are carried in aprobe request frame sent by a non-AP STA, to request a communicationparameter of an AP MLD.

As shown in FIG. 11 a , the requested MLD element includes fields suchas “element ID”, “length”, “element ID extension”, “common information”,and “request MLD configuration”. The “common information” field includesa “request type” subfield.

In an implementation, the “request MLD configuration” indicatesrequested communication parameters of different AP MLDs. In this case,the “request type field” may alternatively not exist.

Specifically, the “request MLD configuration” includes an “MLD address”field. The “MLD address” indicates a requested address of an AP MLD. The“MLD address” may also be equivalent to an “MLD identifier”. The MLDidentifier indicates one or more MLDs. Herein, the “MLD address” and the“MLD identifier” may be an MLD MAC address, an MLD index, an MLD ID, ora BSSID index.

In another implementation, the “request type field” indicates requestedcommunication parameters of different AP MLDs. In this case, the “MLDconfiguration request” field is not required, or a quantity of “MLDconfiguration request” fields is zero.

Specifically, the “request type” in the requested MLD element may be setto different values to indicate requesting for the communicationparameters of different AP MLDs. Using the first indication informationin Embodiment 1 as an example, the request type may be set to 1 bit.

Manner 1: A value of the 1 bit is 1, indicating that a communicationparameter of an AP MLD in which a first AP is located is requested, and0 indicates that only a communication parameter of the first AP isrequested.

Using the second indication information in Embodiment 2 as an example,the request type may be set to 1 bit or a plurality of bits.

(1) When the request type is indicated by 1 bit:

Manner 1: When a value of the 1 bit is 1, it indicates that acommunication parameter of an AP MLD in which a second AP is located isrequested, and when a value of the 1 bit is 0, it indicates that only acommunication parameter of the second AP is requested.

Manner 2: When the value of the 1 bit is 1, it indicates that thecommunication parameter of the AP MLD in which the second AP is locatedand a communication parameter of another AP MLD in which another APbelonging to a same MBSSID set as the second AP is located arerequested, and 0 indicates that only the communication parameter of thesecond AP is requested.

Manner 3: When the value of the 1 bit is 1, it indicates that thecommunication parameter of the AP MLD in which the second AP is locatedand the communication parameter of the another AP MLD are requested, and0 indicates that only the communication parameter of the second AP isrequested. The “another AP MLD” herein includes an AP MLD in whichanother nontransmitted BSSID AP belonging to the same MBSSID set as thesecond AP is located and/or an AP MLD in which another AP collocatedwith the second AP is located.

Manner 4: When the value of the 1 bit is 1, it indicates that the AP MLDin which the second AP is located is requested, and 0 indicates that thecommunication parameter (excluding the AP MLD in which the second AP islocated) of the another AP MLD in the same MBSSID set as the second APis requested.

Manner 5: When the value of the 1 bit is 1, it indicates that the AP MLDin which the second AP is located is requested, and 0 indicates that thecommunication parameter of the another AP MLD is requested. The “anotherAP MLD” herein includes an AP MLD in which another nontransmitted BSSIDAP belonging to the same MBSSID set as the second AP is located and theAP MLD in which the another AP collocated with the second AP is located.

Manner 6: When the value of the 1 bit is 1, it indicates that the AP MLDin which the second AP is located is requested, and 0 indicates that thecommunication parameter of the another AP MLD is requested. The “anotherAP MLD” herein includes the AP MLD in which the another AP collocatedwith the second AP is located.

The foregoing is merely an example. A case of indication by using the 1bit may alternatively be a variation or a combination of the foregoing.

(2) When the request type is indicated by using a plurality of bits, forexample, 3 bits, the request type may have eight values in total.

A first value indicates that only the communication parameter of thesecond AP is requested.

A second value indicates the communication parameter of the AP MLD inwhich the second AP is located is requested.

A third value indicates the communication parameter of the AP MLD inwhich the second AP is located and the communication parameter of theanother AP MLD in which the another AP belonging to the same MBSSID setas the second AP is located.

A fourth value indicates that the communication parameter of the anotherAP MLD in which the another AP belonging to the same MBSSID set as thesecond AP is located other than the AP MLD in which the second AP islocated is requested.

A fifth value indicates that the communication parameter of the AP MLDin which the second AP is located and the communication parameter of theanother AP MLD are requested. The “another AP MLD” herein includes theAP MLD in which the another AP collocated with the second AP is located.

A sixth value indicates that the communication parameter of the anotherAP MLD other than the AP MLD in which the second AP is located isrequested. The “another AP MLD” herein includes the AP MLD in which theanother AP collocated with the second AP is located.

A seventh value indicates that the communication parameter of the AP MLDin which the second AP is located and the communication parameter of theanother AP MLD are requested. The “another AP MLD” herein includes theAP MLD in which the another nontransmitted BSSID AP belonging to thesame MBSSID set as the second AP is located and the AP MLD in which theanother AP collocated with the second AP is located.

An eighth value indicates that the communication parameter of theanother AP MLD other than the AP MLD in which the second AP is locatedis requested. The “another AP MLD” herein includes the AP MLD in whichthe another nontransmitted BSSID AP belonging to the same MBSSID set asthe second AP is located and the AP MLD in which the another APcollocated with the second AP is located.

Certainly, the first value and the eighth value may use only some of theparameters, or two bits are used to indicate some of the parameters

In this embodiment, an example in which the request type field iscarried in a common information field of the requested MLD element isused for description. In another implementation, the request type fieldmay be further carried in another field, for example, a control field.Details are not described herein.

FIG. 11 a is merely an example. In a standard formulation or technologyevolution process, a name of the requested MLD element or a fieldincluded in the requested MLD element may alternatively be implementedin another manner. This is not limited in this embodiment of thisapplication.

FIG. 11 b is a schematic diagram of another structure of a request MLDelement. The structure of the request MLD element is similar to thestructure of the request MLD element provided in FIG. 11 a , and adifference lies in that:

Specifically, “request the MLD configuration” includes a “BSSID indexbitmap” field. Each bit in the bitmap corresponds to one AP MLD, and abit is set to 0 or 1 to indicate whether to request a corresponding APMLD. For example, a bit is set to 1 to indicate requesting an AP to feedback a communication parameter that is of the AP MLD and thatcorresponds to the bit. In an implementation, the “request MLDconfiguration” indicates requested communication parameters of differentAP MLDs. In this case, the “request type field” may alternatively notexist.

It should be understood that, in this embodiment of this application, itis not excluded that the “requested MLD configuration” and the “requesttype field” in the foregoing two request MLD elements are combined toindicate communication parameters of different AP MLDs.

The request MLD element in FIG. 11 a and FIG. 11 b may further carry alink profile subelement field or a link profile element field.

The link profile subelement or the link profile element carries acommunication parameter of an AP. Alternatively, the link profilesubelement or the link profile element carries a communication parameterof a link.

In this embodiment of this application, the link profile subelement orthe link profile element carried in the probe request frame indicatesthe communication parameter of the AP or the link that requests an APMLD. The link profile subelement or the link profile element carried inthe probe response frame is used to carry the communication parameter ofthe AP of the AP MLD or the link.

When the request MLD element does not carry the link profile subelementor the link profile element, it indicates, by default, thatcommunication parameters of all APs or all links in the entire AP MLDare requested or responded to.

Alternatively, when the request MLD element carries a requested linkindicated by the “link profile subelement”, a field may be used toindicate whether to request all links or one link of the AP MLDcorresponding to the “MLD address or MLD identifier”. The field may be 1bit. For example, if the 1 bit is set to 1, it indicates that all linksof a corresponding AP MLD are known. If the 1 bit is set to 0, itindicates that a link is known. The link may be agreed on according to aprotocol.

FIG. 11 b is merely an example. In a standard formulation or technologyevolution process, a name of the requested MLD element or a fieldincluded in the requested MLD element may alternatively be implementedin another manner. This is not limited in this embodiment of thisapplication.

(3) The following describes a specific implementation of a signalingstructure of a known MLD element. The known MLD element may be used inthe foregoing Embodiment 1 and Embodiment 2.

In this embodiment, one or more known MLD elements are carried in aprobe request frame sent by a non-AP STA, to request a communicationparameter of an AP MLD.

FIG. 12 a shows a structure of a known MLD element. The known MLDelement includes fields such as “element ID”, “length”, “element IDextension”, “common information”, and “known MLD configuration”, wherethe “common information” field optionally further includes a “requesttype” subfield. The “known MLD configuration” subfield may exist or notexist. When the “known MLD configuration” subfield exists, an “MLDaddress” field is included.

The “MLD address” may also be equivalent to an “MLD identifier”, and theMLD identifier indicates one or more MLDs. Herein, the “MLD address” andthe “MLD identifier” may be an MLD MAC address, an MLD index, an MLD ID,or a BSSID index. Same as the request type of the requested MLD elementdescribed in (2), a request type of the known MLD element may also useone to three bits to indicate to request communication parameters ofdifferent AP MLDs. For details, refer to the description in (2), anddetails are not described herein again.

A difference from (2) is that the known MLD profile carries acommunication parameter of an AP MLD that is already known by the non-APSTA, and a second AP does not need to carry a correspondingcommunication parameter in the probe response frame. In other words, thesecond AP carries, in the probe response frame, the communicationparameter of the known AP MLD indicated by removing the MLD address ofthe known MLD profile from the AP MLD requested in the request type.

In this embodiment, an example in which the request type field iscarried in a common information field of the known MLD element is usedfor description. In another implementation, the request type field maybe further carried in another field, for example, a control field.Details are not described herein.

In another implementation, the common information field of the known MLDelement may not include the “request type”, but uses one or more “knownMLD configurations” to indicate that an AP responsible for responding tothe probe request frame is requested to reply with a communicationparameter of another AP MLD other than a corresponding AP MLDcorresponding to the “MLD address”.

FIG. 12 b shows a structure of another known MLD element. The known MLDelement includes fields such as “element ID”, “length”, “element IDextension”, and “BSSID index bitmap”. The “BSSID identifier bitmap”indicates a status of a communication parameter of an AP MLD known bythe non-AP STA that initiates the probe request frame. The APresponsible for sending the probe response frame replies withcommunication parameters of AP MLDs other than the known AP MLDindicated by the BSSID index bitmap in all AP MLDs.

The “all AP MLDs” in the foregoing implementation may be a known oragreed AP MLD in which another AP in an MBSSID set that belongs to asame MBSSID as the AP is located, and/or an AP MLD in which another APcollocated with the AP is located.

FIG. 12C shows a structure of another known MLD element. The known MLDelement includes fields such as “element ID”, “length”, “element IDextension”, and “multilink element”. The “multilink element” carries“MLD common information” and “link profile subelement”. The “MLD commoninformation” may carry “MLD address or MLD identifier”, and the “linkprofile subelement” indicates a known link in a plurality of links inthe AP MLD corresponding to the “MLD address or MLD identifier”.

The AP that responds to the probe request frame replies with acommunication parameter of another link other than the AP MLDcorresponding to the “MLD address or MLD identifier” and other than theknown links indicated by the “link profile subelement”.

A manner of a known link indicated by the “link profile subelement” maybe carrying an identifier or an index number of the known link, or maybe carrying a link index bitmap, used to indicate which links are known.

The “link profile subelement” indicates a manner of a known link.Alternatively, a field may be used to indicate whether all links of theAP MLD corresponding to the “MLD address or MLD identifier” or one linkis known. The field may be 1 bit. For example, if the 1 bit is set to 1,it indicates that all links of a corresponding AP MLD are known. If the1 bit is set to 0, it indicates that a link is known. The link may beagreed on according to a protocol.

In this embodiment, the “link profile subelement” may be directlycarried in the known MLD element, or may be carried in the known MLDelement by using a multi-link element.

The multi-link element, known MLD element and the request MLD elementdescribed in the foregoing embodiment may be combined depending on asituation, and carried in the probe request frame to implement differentfunctions of detecting communication parameters of the plurality oflinks of the AP MLD and the AP MLD.

The following describes an implementation of the probe response frame.

In Embodiment 1, regardless of whether the non-AP STA sends the proberequest frame in the implicit indication manner or the explicitindication manner, if the logical AP receiving the probe request frameis configured as the nontransmitted BSSID, a probe response frame isreplied by using another transmitted BSSID AP that belongs to the sameMSSID set.

When replying with the probe response frame to the non-AP STA, thetransmitted BSSID AP carries information about the nontransmitted BSSIDAP in the multiple BSSID element of the probe response frame. As shownin FIG. 10 , the transmitted BSSID AP carries, in the multiple BSSIDelement, a nontransmitted BSSID profile corresponding to thenontransmitted BSSID AP, to carry a communication parameter of thenontransmitted BSSID AP, and carries, in the multi-link element includedin the nontransmitted BSSID profile corresponding to the nontransmittedBSSID AP, a communication parameter of another AP in the AP MLD in whichthe nontransmitted BSSID AP is located. Specifically, the communicationparameter of the another AP is carried in a link profile subelement.There may be a plurality of link profile subelements, to correspond tocommunication parameters of a plurality of APs.

For example, as shown in FIG. 4 , the AP 11 carries, in the proberesponse frame replied to the non-AP STA, the communication parametersof the plurality of links supported by the AP MLD 2. Specifically, thecommunication parameters may be carried in the multiple BSSID element,that is, the multiple BSSID element carries the nontransmitted BSSIDprofile corresponding to the AP 12 to carry the information about the AP12. The multi-link element is carried in the nontransmitted BSSIDprofile corresponding to the AP 12 to carry the information about the AP22.

Correspondingly, in Embodiment 2, regardless of whether the non-AP STAsends the probe request frame in the implicit indication manner or theexplicit indication manner, if the logical AP receiving the proberequest frame is the transmitted BSSID AP, the logical AP may directlyreply with the probe response frame to the non-AP STA.

When replying with the probe response frame to the non-AP STA, thetransmitted BSSID AP may carry the information about the nontransmittedBSSID AP in the multiple BSSID element of the probe response frame.

As shown in FIG. 10 , the transmitted BSSID AP carries, in the multipleBSSID element, a nontransmitted BSSID profile corresponding to thenontransmitted BSSID AP, to carry a communication parameter of thenontransmitted BSSID AP, and carries, in the multi-link element includedin the nontransmitted BSSID profile corresponding to the nontransmittedBSSID AP, a communication parameter of another AP in the AP MLD in whichthe nontransmitted BSSID AP is located.

For example, as shown in FIG. 4 , the AP 21 is the transmitted BSSID AP,and after the AP 21 receives the probe request frame, the AP21 carries,in the probe response frame replied to the non-AP STA, communicationparameters of one or more links supported by one or more AP MLDs in theAP MLD 1, the AP MLD 2, and the AP MLD 3 in which the AP 21 is located,that is, communication parameters of one or more APs in the AP MLD 1,the AP MLD 2, and the AP MLD 3.

Specifically, when the probe request frame requests the communicationparameter of the AP MLD 1 in which the AP 21 is located, thecommunication parameter of the AP MLD 1 is carried in the multi-linkelement in the probe response frame. Specifically, communicationparameters of the AP 11, the AP 21, and the AP 31 may be separatelycarried in three link profile subelements in the multi-link element.

When the AP MLD requested by the probe request frame further includescommunication parameters of the AP MLD 2 and/or the AP MLD 3, thecommunication parameters of the AP MLD 2 and the AP MLD 3 may be carriedin the multiple BSSID element in the probe response frame. To bespecific, two nontransmitted BSSID profiles corresponding to the AP 21are carried in the multiple BSSID element to respectively carrycommunication parameters of the AP 22 and the AP 23. The link profilesubelement of the multi-link element is carried in the nontransmittedBSSID profile corresponding to the AP 22 to carry information about theAP 12. The link profile subelement of the multi-link element is carriedin the nontransmitted BSSID profile corresponding to the AP 23 to carrya communication parameter of the AP 33.

In various implementations of Embodiment 1, Embodiment 2, and Embodiment3, when the non-AP MLD does not need to obtain a complete communicationparameter of the AP in the AP MLD, but needs to obtain only someinformation elements of the AP, the non-AP MLD may carry an identifierlist of an information element in the probe request frame, to requestthe AP MLD to reply with content of a corresponding information element.As shown in FIG. 13 , the information element identifier list is carriedby using a probing element, for example, a “list of element IDs (list ofelement IDs)”. Each element ID corresponds to a requested informationelement. In still another implementation, the non-AP STA may directlycarry a non-inheritance element in the probe request to carry somerequested information elements.

Correspondingly, if the probe response frame includes communicationparameters of a plurality of APs, a communication parameter of each APincludes content of an information element corresponding to an elementID carried in the list of element IDs.

Alternatively, in the probe request frame, each AP carries an identifierlist of an information element, and information elements of differentcommunication parameters may be requested for different APs. In thiscase, the probe response frame carries an information element of acommunication parameter corresponding to each AP.

The information element described in this embodiment is partialinformation of the communication parameter of the AP described above.

According to this embodiment, some communication parameters of the APcan be flexibly requested, thereby reducing request and feedbackoverheads.

The following describes in detail an apparatus provided in embodimentsof this application.

In embodiments of this application, the access point AP (for example, anAP in an AP multi-link device) or the station may be divided intofunction modules based on the foregoing method examples. For example,the functional modules may be obtained through division based oncorresponding functions, or two or more functions may be integrated intoone processing module. The integrated module may be implemented in aform of hardware, or may be implemented in a form of a softwarefunctional module. It should be noted that, in the embodiments of thisapplication, division into the modules is an example, and is merelylogical function division. In an actual implementation, another divisionmanner may be used.

When an integrated unit is used, FIG. 14 is a possible schematic diagramof a structure of a communication apparatus 1400. The communicationapparatus 1400 may be a multi-link device, or a chip or a processingsystem in a multi-link device. The communication apparatus 1400 mayperform operations of the multi-link device in the foregoing methodembodiments. The communication apparatus 1400 includes a processing unit1401 and a transceiver unit 1402.

For example, the communication apparatus 1400 is the foregoing accesspoint AP (for example, an AP in an AP multi-link device) or the station.

For example, the communication apparatus 1400 is the access point or achip in the access point.

The processing unit 1401 may be configured to control and manage anaction of the communication apparatus 1400. For example, a probe requestframe is generated. For another example, an operation of the transceiverunit 1402 is controlled. Optionally, if the communication apparatus 1400includes a storage unit, the processing unit 1401 may further execute aprogram or instructions stored in the storage unit, so that thecommunication apparatus 1400 implements the method and functions in anyone of the foregoing embodiments.

For example, the processing unit 1401 may control the transceiver unitto perform step S101 in FIG. 5 , S201 in FIG. 6 , or another process ofthe technology described in this specification. All related content ofthe steps in the foregoing method embodiments may be cited in functiondescriptions of the corresponding functional modules. Details are notdescribed herein again.

For example, the processing unit 1401 may control the transceiver unitto perform step S102 in FIG. 5 , S202 in FIG. 6 , or another process ofthe technology described in this specification. All related content ofthe steps in the foregoing method embodiments may be cited in functiondescriptions of the corresponding functional modules. Details are notdescribed herein again.

For example, the transceiver unit 1402 may send and receive data orsignaling transmitted on one link, or may send and receive data orsignaling transmitted on a plurality of links. Optionally, thetransceiver unit 1402 may be one transceiver module, or may include aplurality of transceiver modules. When the transceiver unit 1402 is onetransceiver module, the transceiver module may send and receive data ona plurality of links. For example, if a first multi-link device operateson two links, when the transceiver unit 1402 includes two transceivermodules, one of the transceiver modules operates on one link, and theother transceiver module operates on the other link. For example, thetransceiver unit 1402 may be configured to perform step S101 in FIG. 5 ,step S201 in FIG. 6 , or another process of the technology described inthis specification. All related content of the steps in the foregoingmethod embodiments may be cited in function descriptions of thecorresponding functional modules. Details are not described hereinagain.

For example, the communication apparatus 1400 may be the communicationapparatus shown in FIG. 15 , the processing unit 1401 may be theprocessor 1501 in FIG. 15 , and the transceiver unit 1402 may be thetransceiver 1503 in FIG. 15 . Optionally, the communication apparatus1400 may further include a memory. The memory is configured to storecorresponding program code and data that are for the communicationapparatus 1400 to perform any one of the foregoing communication methodsbetween multi-link devices. Descriptions of all related content of thecomponents in FIG. 15 may be cited in function description ofcorresponding components of the communication apparatus 1400, anddetails are not described herein again.

For example, the communication apparatus 1400 may alternatively be achip or a processor, the processing unit 1401 is a processing circuit inthe chip or the processor, the transceiver unit 1402 may be aninput/output circuit in the chip or the processor, the input/outputcircuit is an interface for mutual communication or data exchangebetween the chip or the processor and another coupled component. It canbe ensured that signaling or data information or program instructionsare input to the chip or the processor for processing, processed data orsignaling is output to the another coupled component, and the firstmulti-link device in which the chip or the processor is installed iscontrolled to implement functions.

For another example, the communication apparatus 1400 is the foregoingstation or the chip in the foregoing station.

The processing unit 1401 may be configured to control and manage anaction of the communication apparatus 1400. For example, a probe requestframe or a probe response frame is generated. For another example, anoperation of the transceiver unit 1402 is controlled. Optionally, if thecommunication apparatus 1400 includes a storage unit, the processingunit 1401 may further execute a program or instructions stored in thestorage unit, so that the communication apparatus 1400 implements themethod and functions in any one of the foregoing embodiments.

For example, the processing unit 1401 may be configured to generate aprobe request frame or a probe response frame. All related content ofthe steps in the foregoing method embodiments may be cited in functiondescriptions of the corresponding function modules. Details are notdescribed herein again.

For example, the transceiver unit 1402 may send and receive data orsignaling transmitted on one link, or may send and receive data orsignaling transmitted on a plurality of links. Optionally, thetransceiver unit 1402 may be one transceiver module, or may include aplurality of transceiver modules. When the transceiver unit 1402 is onetransceiver module, the transceiver module may send and receive data ona plurality of links. For example, if a first station operates on twolinks, when the transceiver unit 1402 includes two transceiver modules,one of the transceiver modules operates on one link, and the othertransceiver module operates on the other link. All related content ofthe steps in the foregoing method embodiments may be cited in functiondescriptions of the corresponding functional modules. Details are notdescribed herein again.

For example, the communication apparatus 1400 may be the communicationapparatus shown in FIG. 15 , the processing unit 1401 may be theprocessor 1501 in FIG. 15 , and the transceiver unit 1402 may be thetransceiver 1503 in FIG. 15 . Optionally, the communication apparatus1400 may further include a memory. The memory is configured to storeprogram code and data that are for the communication apparatus 1400 toperform any one of the foregoing embodiments. Descriptions of allrelated content of the components in FIG. 15 may be cited in functiondescription of corresponding components of the communication apparatus1400, and details are not described herein again.

For example, the communication apparatus 1400 may alternatively be achip or a processor, the processing unit 1401 is a processing circuit inthe chip or the processor, the transceiver unit 1402 may be aninput/output circuit in the chip or the processor, the input/outputcircuit is an interface for mutual communication or data exchangebetween the chip or the processor and another coupled component. It canbe ensured that signaling or data information or program instructionsare input to the chip or the processor for processing, processed data orsignaling is output to the another coupled component, and the firstmulti-link device in which the chip or the processor is installed iscontrolled to implement functions.

It should be noted that, in the apparatus embodiment part, forstructures of the probe request frame and the probe response frame,refer to descriptions in the foregoing embodiments. Details are notdescribed herein again.

FIG. 15 shows a communication apparatus 1500 according to an embodimentof this application. The apparatus may be an access point AP (forexample, an AP in an AP multi-link device) or a station in the foregoingembodiments, or may be an access point AP (for example, an AP in an APmulti-link device) or a chip or a processing system in a station, andcan implement a method and a function in any embodiment of thisapplication. Due to a difference between integration degrees, thecommunication apparatus may include one or more of the components shownin FIG. 15 . The components shown in FIG. 15 may include at least oneprocessor 1501, a memory 1502, a transceiver 1503, and a communicationbus 1504.

The following describes each composition component of the communicationapparatus 1500 in detail with reference to FIG. 15 .

The processor 1501 is a control center of the communication apparatus150 o, and may be one processor or may be a collective term of aplurality of processing elements. For example, the processor 1501 is acentral processing unit (CPU), an application-specific integratedcircuit (Application Specific Integrated Circuit, ASIC), or one or moreintegrated circuits configured to implement embodiments of thisapplication, for example, one or more microprocessors (digital signalprocessor, DSP), or one or more field programmable gate arrays (FPGA).The processor 1501 may implement various functions of the communicationdevice by running or executing a software program stored in the memory1502 and invoking data stored in the memory 1502. During specificimplementation, in an embodiment, the processor 1501 may include one ormore CPUs, for example, a CPU 0 and a CPU 1 shown in FIG. 15 .

During specific implementation, in an embodiment, the communicationapparatus 1500 may include a plurality of processors, for example, theprocessor 1501 and a processor 1505 shown in FIG. 15 . Each of theprocessors may be a single-core processor (single-CPU) or may be amulti-core processor (multi-CPU). The processor herein may be one ormore communication devices, circuits, and/or processing cores configuredto process data (for example, computer program instructions).

The memory 1502 may be a read-only memory (ROM) or another type ofstatic storage communication device that can store static informationand instructions; or a random access memory (RAM) or another type ofdynamic storage communication device that can store information andinstructions. The memory may alternatively be an electrically erasableprogrammable read-only memory (EEPROM), a compact disc read-only memory(CD-ROM) or another compact disc storage, an optical disc storage(including a compact disc, a laser disc, an optical disc, a digitalversatile disc, a Blu-ray disc, or the like), a magnetic disk storagemedium or another magnetic storage communication device, or any othermedium that can be used to carry or store expected program code in aform of instructions or a data structure and that is accessible by acomputer, but is not limited thereto. The memory 1502 may existindependently, or may be connected to the processor 1501 by using thecommunication bus 1504. Alternatively, the memory 1502 may be integratedwith the processor 1501. The memory 1502 is configured to store asoftware program for executing the solution of this application, and theprocessor 1501 controls execution of the software program.

The transceiver 1503 is configured to communicate with another device(for example, the station STA 102 or the STA 202 in the embodiment shownin FIG. 1 ). Certainly, the transceiver 1503 may be further configuredto communicate with a communication network, for example, the Ethernet,a radio access network (RAN), or a wireless local area network (WLAN).The transceiver 1503 may include a receiving unit to implement areceiving function, and a transmitting unit to implement a transmittingfunction.

The communication bus 1504 may be an industry standard architecture(ISA) bus, a peripheral component interconnect (PCI) bus, an extendedindustry standard architecture (EISA) bus, or the like. The bus may beclassified into an address bus, a data bus, a control bus, and the like.For ease of representation, only one thick line is used to represent thebus in FIG. 15 , but this does not mean that there is only one bus oronly one type of bus.

For example, the communication apparatus 1500 is a complete device. Thecommunication apparatus may include a processor 1501, a memory 1502, atransceiver 1503, and a communication bus 1504. Optionally, thecommunication apparatus may further include another component, forexample, a display.

Optionally, the communication apparatus 1500 is an access point AP (forexample, an AP in an AP multi-link device), and may be configured toimplement the methods and functions related to the AP in the foregoingembodiments. For example, the memory stores a computer program(instructions). When the processor invokes the computer program, theforegoing method and function are implemented. For example, theprocessor is configured to generate a probe response frame, and thetransceiver is configured to receive the probe request frame and send aprobe response frame. For example, the processor is configured tocontrol the transceiver to perform step S102. Certainly, a process ofgenerating the probe response frame in step S102 may also be completedby the processor. For another example, the processor is configured tocontrol the transceiver to perform step S2 o 2. Certainly, a process ofgenerating the probe response frame in step S2 o 2 may also be completedby the processor.

In still another implementation, the communication apparatus 1500 is astation, and may be configured to implement the method and the functionof the station in the foregoing embodiments. For example, the memorystores a computer program. When the processor invokes the computerprogram, the foregoing method and function are implemented. For example,the processor is configured to generate signaling or a frame (forexample, a probe request frame), and the transceiver is configured tosend the signaling or the frame (for example, send a probe request frameand receive a probe response frame). For example, the processor isconfigured to control the transceiver to send the probe request frame instep S101, and then the processor determines a structure of a multi-APmulti-link device and information about each AP based on the proberesponse frame, and may further determine an AP to be associated with.For another example, for example, the processor is configured to controlthe transceiver to send the probe request frame in step S201 and controlthe transceiver to receive the probe response frame fed back by the APin S202. Then the processor determines a structure of the multi-APmulti-link device and information about each AP based on the proberesponse frame, and further determines the AP to be associated with

For another example, the communication apparatus 1500 is a chip systemor a processing system in the access point AP, so that a device in whichthe chip system or the processing system is installed implements themethod and the function related to the AP in the foregoing embodiments.In this case, the communication apparatus 1500 may include somecomponents shown in FIG. 15 . For example, the communication apparatus1500 includes a processor. The processor may be coupled to a memory,invoke instructions in the memory, and execute the instructions, so thata device configured or installed with the chip system or the processingsystem implements the methods and the functions in the foregoingembodiments. Optionally, the memory may be a component in the chipsystem or the processing system, or may be a coupled/connected componentoutside the chip system or the processing system. For example, the chipsystem or the processing system is installed in the access point AP (forexample, a reporting AP in an AP multi-link device), so that the accesspoint AP may perform step S102 or step S202 in the foregoing embodiment.

For another example, the communication apparatus 1500 is a chip systemor a processing system in a station, so that a device in which the chipsystem or the processing system is installed implements the method andthe function related to the station in the foregoing embodiments. Inthis case, the communication apparatus 1500 may include some componentsshown in FIG. 15 . For example, the communication apparatus 1500includes a processor. The processor may be coupled to a memory, invokeinstructions in the memory, and execute the instructions, so that adevice configured or installed with the chip system or the processingsystem implements the methods and the functions in the foregoingembodiments. Optionally, the memory may be a component in the chipsystem or the processing system, or may be a coupled/connected componentoutside the chip system or the processing system. In an example, thechip system or the processing system is installed in the station, sothat the station can perform step S101 or step S201 in the foregoingembodiment.

The chip system or processing system may support communication based on802.11 series protocols, for example, 802.11be, 802.11ax, and 802.11ac.The chip system may be installed in devices in various scenarios thatsupport WLAN transmission. The devices in the WLAN transmissionscenarios are described at the beginning of this specification, anddetails are not described herein.

An embodiment of this application further provides a computer-readablestorage medium. The computer-readable storage medium stores computerprogram code. When the foregoing processor executes the computer programcode, an electronic device (for example, an AP or a station) in whichthe processor is located is enabled to perform the method in anyembodiment.

An embodiment of this application further provides a computer programproduct. When the computer program product runs on a computer, thecomputer (for example, an AP or a station) is enabled to perform themethod in any embodiment.

An embodiment of this application further provides a communicationapparatus. The apparatus may exist in a product form of a chip. Astructure of the apparatus includes a processor and an interfacecircuit. The processor is configured to communicate with anotherapparatus through a receiving circuit, to enable the apparatus toperform the method in any embodiment.

An embodiment of this application further provides a communicationsystem. The communication system includes the foregoing access point AP(for example, an AP in an AP multi-link device) and a station. Theaccess point AP (for example, a reporting AP in an AP multi-link device)and the station may perform the method in any one of the foregoingembodiments (for example, the methods in FIG. 5 and FIG. 6 ). Method oralgorithm steps described in combination with the content disclosed inthis application may be implemented by hardware, or may be implementedby a processor by executing software instructions. The softwareinstructions may include a corresponding software module. The softwaremodule may be stored in a random access memory (RAM), a flash memory, anerasable programmable read-only memory (Erasable Programmable ROM,EPROM), an electrically erasable programmable read-only memory(Electrically EPROM, EEPROM), a register, a hard disk, a removable harddisk, a compact disc read-only memory (CD-ROM), or any other form ofstorage medium well-known in the art. For example, a storage medium iscoupled to a processor, so that the processor can read information fromthe storage medium or write information into the storage medium.Certainly, the storage medium may be a component of the processor. Theprocessor and the storage medium may be disposed in an ASIC. Inaddition, the ASIC may be located in a core network interface device.Certainly, the processor and the storage medium may exist in the corenetwork interface device as discrete components.

A person skilled in the art should be aware that in the foregoing one ormore examples, functions described in this application may beimplemented by hardware, software, firmware, or any combination thereof.When the functions are implemented by software, the foregoing functionsmay be stored in a computer-readable medium or transmitted as one ormore instructions or code in a computer-readable medium. Thecomputer-readable medium includes a computer-readable storage medium anda communication medium. The communication medium includes any mediumthat facilitates transmission of a computer program from one place toanother. The storage medium may be any available medium accessible to ageneral-purpose or a special-purpose computer.

In the foregoing specific implementations, the objectives, technicalsolutions, and beneficial effects of this application are furtherdescribed in detail. It should be understood that the foregoingdescriptions are merely specific implementations of this application,but are not intended to limit the protection scope of this application.Any modification, equivalent replacement, improvement, or the like madebased on the technical solutions of this application shall fall withinthe protection scope of this application.

1-18. (canceled)
 19. A station in a wireless local area network (WLAN),comprising: a processor, configured to generate a probe request frame,wherein the probe request frame requests an first access point (AP) tofeed back a communication parameter that is of an AP multi-link device(MLD) and that is related to the first AP, the first AP being atransmitted basic service set identifier (BSSID) AP, and thecommunication parameter of the AP MLD comprising communicationparameters of a plurality of links supported by the AP MLD, and whereinthe probe request frame carries first lists of identifiers of firstinformation elements, each first list of identifiers corresponding to anAP in the AP MLD, to request content of the first information elementsof the corresponding AP in the AP MLD; and a transceiver, configured tosend the probe request frame to the first AP.
 20. The station accordingto claim 19, wherein the probe request frame carries first indicationinformation, and the first indication information indicates the first APto feed back the communication parameter that is of the AP MLD and thatis related to the first AP.
 21. The station according to claim 20,wherein the communication parameter that is of the AP MLD and that isrelated to the first AP comprises at least one of following: acommunication parameter of the AP MLD in which the first AP is located;a communication parameter of an AP MLD in which another AP belonging toa same multiple transmitted basic service set identifier (MBSSID) set asthe first AP is located; or a communication parameter of an AP MLD inwhich another AP collocated with the first AP is located.
 22. Thestation according to claim 20, wherein the first indication informationis carried in the probe request frame, the first indication informationindicates an MLD identifier or an MLD address, and the MLD identifier orthe MLD address indicates the first AP to feed back a communicationparameter of an AP MLD corresponding to the MLD identifier or the MLDaddress.
 23. The station according to claim 19, wherein the proberequest frame further carries a second list of identifiers of secondinformation elements, to request to acquire the second informationelements of each requested AP in the AP MLD.
 24. The station accordingto claim 23, wherein the transceiver is further configured to receive aprobe response frame, the probe response frame comprises communicationparameters of a plurality of APs in the AP MLD, and a communicationparameter of each AP in the plurality of APs comprises content of asecond information element corresponding to an identifier of the secondlist of identifiers carried in the probe request frame.
 25. The stationaccording to claim 19, wherein the transceiver is further configured toreceive a probe response frame comprises an information element of acommunication parameter corresponding to each corresponding AP in the APMLD.
 26. The station according to claim 19, wherein the first lists ofidentifiers of the first information elements are carried in amulti-link element of the probe request frame.
 27. A method comprising:generating, by a station in a wireless local area network (WLAN), aprobe request frame, wherein the probe request frame requests a firstaccess point (AP) to feed back a communication parameter that is of anAP multi-link device (MLD) and that is related to the first AP, thefirst AP being a transmitted basic service set identifier (BSSID) AP,and the communication parameter of the AP MLD comprising communicationparameters of a plurality of links supported by the AP MLD, and whereinthe probe request frame carries first lists of identifiers of firstinformation elements, each first list of identifiers corresponding to anAP in the AP MLD, to request content of the first information elementsof the corresponding AP in the AP MLD; and sending, by the station, theprobe request frame to the first AP.
 28. The method according to claim27, wherein the probe request frame carries first indicationinformation, and the first indication information indicates the first APto feed back the communication parameter that is of the AP MLD and thatis related to the first AP.
 29. The method according to claim 28,wherein the communication parameter that is of the AP MLD and that isrelated to the first AP comprises at least one of following: acommunication parameter of the AP MLD in which the first AP is located;a communication parameter of an AP MLD in which another AP belonging toa same multiple transmitted basic service set identifier MBSSID set asthe first AP is located; or a communication parameter of an AP MLD inwhich another AP collocated with the first AP is located.
 30. The methodaccording to claim 28, wherein the first indication information iscarried in the probe request frame, the first indication informationindicates an MLD identifier or an MLD address, and the MLD identifier orthe MLD address indicates the first AP to feed back a communicationparameter of an AP MLD corresponding to the MLD identifier or the MLDaddress.
 31. The method according to claim 27, wherein the probe requestframe further carries a second list of identifiers of second informationelements, to request to acquire the second information elements of eachrequested AP in the AP MLD.
 32. The method according to claim 31,further comprising: receiving, by the station, a probe response frame,wherein the probe response frame comprises communication parameters of aplurality of APs in the AP MLD, and a communication parameter of each APin the plurality of APs comprises content of a second informationelement corresponding to an identifier of the second list of identifierscarried in the probe request frame.
 33. The method according to claim27, further comprising: receiving, by the station, a probe responseframe, wherein the probe response frame comprises an information elementof a communication parameter corresponding to each corresponding AP inthe AP MLD.
 34. The method according to claim 27, wherein the firstlists of identifiers of the first information elements are carried in amulti-link element of the probe request frame.
 35. A non-access pointstation (non-AP STA) multi-link device (MLD), comprising at least oneSTA, wherein the at least one STA includes a station according to claim19.